Personally, I think of it as a middle ground here. I do agree with what you say though. The reason for the French invasion of Algeria was only to shore up support in home (which ultimately failed shortly after they took Algiers because the July Revolution happened literally three weeks afterwards), not to end the Mediterranean slave trade. Napoleon has nothing to prove and though it is unknown whether or not he would have issues at home by 1830 ITTL, it is also hard to say if Napoleon would still be alive by 1830. On paper he should, he did die age 51, but whether if it was the results of the poison that weakened over time and failed to kill him then and there, or by more natural causes (or by something that could be treatable in France but not in Saint Helena) is so up in the air that only the man upstairs knows for sure. Either way, if Nappy lives to see 1830, or if it happens earlier, it's not going to be Nappy to do it.
With that being said however, just because Nappy wouldn't do it doesn't mean that you can't have someone else do the job. As you said Kurd, the Spanish monarchy needs to rebuild its legitimacy after the debacle with Ferdinand and they could definitely benefit from this scheme. As an alternative to throw around, the Neapolitans under Joseph Bonaparte could also play this role as well, being probably the only significant regional power in Italy that isn't one of the current continental hegemons that control much of the boot. I'd also make an argument for the Bourbons of Sicily proper, but I dunno if they're even still around.
^This. We're far and away removed from the Scramble for Africa and no country was willing to make a play at conquering empty desert this early into the game, just to put in perspective, the conquest of Algeria, not Algiers or the coastline, but the lands that would make up the modern day People's Democratic Republic of Algeria, wasn't completed until 1903, 73 years after the conquest of Algiers.