Kevin is certainly retarded but I think you're giving him too much credit here by granting him a philosophy, he's simply repeating what other communists say. It's pretty much been an axiom since Marx and Engels that scarcity does not exist not in some technologically advanced future but the here and now and is only caused for everyone by the capitalists hoarding through the fiction of property. Even non-communists sympathetic to the "left" (and sometimes the "right") say this constantly about all kinds of things.
Because Kevin is stupid he doesn't understand why he can't just have whatever he wants, possibly because this has been his experience, so when this happens (for any reason) and he's told it's the fault of someone else being malicious against him personally he accepts it as true. The "communism" he supports, not really as I and others have shown throughout his thread*, is as you got to at the end there merely the language he's stolen to frame the difference between reality he does not like (capitalism) and the utopia he imagines himself entitled to by the fact of his existence (communism) and is most likely the result of social factors related to who he's associated with. It's entirely possible that an alternative Kevin would simply ascribe these same things to the work of Satan and longed for the day when Goddess accepted him into her ample bosom, we could come up with a multitude of similar hypothetical Kevin's with the same mindset (some even have threads here) but I think that one is an easy example familiar enough to everyone and that Kevin would dislike.
I think it's highly likely that Kevin would struggle to conceive of a world or even a universe outside of his personal existence unless it's tied to some fictional universe he consooms.
*example since I just came back across these on my hard drive today:
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