I'm not sure if you have read my post correctly. the POD starts after the Anschluss, not before.
Additionally, It didn't say
how Italy declared war. By "Roman Empire" I don't mean that they try to get 110AD borders back but rather what they planned in WW2. Their Ambitions would probably look like
this but dont have to be. You know, that classic expansionist ambitions.
It doesn't mean that Italy made an aggressive strike. Maybe Spain or hungary, or even Japan (we don't know as I concentrated more on Germany-France-Poland-Britain)) as described in the text with "against all the fascist regimes". Due to a lacking Germany, Italy might look around to search some allies. If they'll get bullied by France, Germany, Britain or whatsoever (could imagine Hungary stumbling into Germany/German interests and "Whoops, WW2") and Italy would declare war on them to stand with their ally (The same happened in OTL Japan-Germany, to point that out).
it's possible and it surely is not ASB. Or if we define it that way, then every alternate history is ASB.