Beyond the legal problem of declaring himself emperor, there's the simple fact that the (Western) Roman Empire was a legal fiction. The Empire had long since withered away. Though some invader tribes pledged a modicum of allegiance to Rome, the truth was that all of Western Rome outside of Italy was under the control of one barbarian kingdom or another.
When the throne in Rome was left empty, no one in the rest of the "Empire" really noticed a change.
The Empire hadn't been in control of those territories in a long time. Does that mean it's no longer the Roman Empire, simply because it lost control of Gaul, Spain and Africa ?
Also, Odoacer did have influence on the Med:
He achieved a solid diplomatic coup by inducing the Vandal king
Gaiseric to cede to him Sicily.
for the first time since the mid-3rd century copper coins were issues with the legend
S(enatus) C(onsulto). Jones describes these coins as "fine big copper pieces", which were "a great improvement on the miserable little
nummi hitherto current", and not only were they copied by the Vandals in Africa, but they formed the basis of the currency reform by
Anastasius in the Eastern Empire.
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Yeah. If I may fly my contrarian colors--Romulus Augustus was merely the latest of quite a few pretenders, and Julius Nepos the latest of Eastern Empire backed strongmen whose title and authority were virtually meaningless. Personally, I count the last REAL Western Roman Emperor as Valentinian III--after him, "Western Emperors" are little more than local strongmen whose standing in Western Europe isn't any better than the various kings and chiefs that surround them, with a large number of them being usurpers.
And there is another question: - what is a 'legitimate Roman Emperor'? As opposed to 'usurper'.
But don't tell me that a legitimate Roman Emperor is someone appointed or proclaimed by the Roman Senate. That is not true and not valid since Octavianus Augustus.
* Now here I am speaking about the Western Roman Empire of the V-th century A.D. mostly. But it is true for the IV-th century as well.
What is a 'true' Roman Emperor?
That is someone proclaimed such by somebody and strong enough to enforce his authority over some part of the Roman territory for some period of time. (It so happened that he had to be ethnic Roman to be called that title).
What I would not call a 'true' emperor - a puppet, a Roman nobody of high birth fom noble senatorial family of pure ethnic Roman blood, a figurehead who was proclaimed an emperor by some Germanic warlord, a strongman lacking 'Roman ethnicity' to be proclaimed Emperor himself.
For me, being the legal emperor of Rome means:
1. having the former emperor no longer hold that office (death or resignation)
2. be proclaimed emperor by the Senate
There were multiple times throughout the empire's history where more than one person claimed to hold the office, however, the legitimate one was the guy who got the senate's backing.
If you were not proclaimed by the Senate, you were not the emperor.
As for the other criteria, an emperor is an emperor, regardless of how much territory he controls or wether he is a puppet or his successor fails or whatever. Some emperors are powerfull, some are not, but they're still emperors.
Is Elizabeth not the queen of Britain, even though she has little to no power ?
If Zeno gave a damn about the pretense of the western throne, then he would've taken action when Odoacer began ruling without puppet emperors. But since he didn't, he must have realized that a symbolic title wasn't worth the trouble.
Well, he did actually. He had the Rugians attack Odoacer, and, when these failed, he sent the Goths.
He was a bit busy with Illus' revolt to do anything more...
What I mean is that Odoacer styling himself emperor wouldn't have worsened his situation, as some suspect. Of course, it wouldn't have helped him either. He still would've been just as vulnerable as he had been in OTL, and still would've been defeated by Theoderic. But the difference is that Theoderic would've inherited the title of Western Roman Emperor, rather than the title of King of Italy.
He absolutely needed the support of the Roman nobility. That's why he went out of his way to appease them, granting them titles and power and prestige.
But let's say he doesn't. He forces the Senate in Rome to declare him emperor at swordpoint and executes anyone who publicly disagrees.
Then what ?
The nobles are going to become dissatisfied. Tax returns will begin to dry up, assassination attempts will take place and most of Italy will become restless. This means Odoacer now has less money to hire mercenaries and has to disperse a lot (probably most) of his small force of Heruli troughout Italy to keep everyone in line. This puts him at a severe military disatvantage.
Next, Zeno bribes the Rugians to attack, which they do, as OTL. Either they win, or they loose, but weaken Odoacer in the proces, most likely enough for him to succumb to either a rebellion by the Romans backed by a small force from the east headed by Nepos. Or, if he wins even that, then against the Burgundians and Vandals, who, like sharks, will sense blood in the water and strike the critically weakened state in Italy.