My point is that it's only unsportsmanlike in this particular case if it makes the defense think the snap is not imminent.

It appears that the fake injury was concurrent with or after the snap, so it was not before the snap and is not unsportsmanlike.

Of course, if there's any doubt in whether it happened before the snap, I'm throwing the flag.

No. It's still unsportsmanlike.

However, does that change the enforcement (i.e. live ball vs dead ball foul)?

USC during a live ball is succeeding spot enforcement.

Are you going by the inclusion of one implies the exclusion of others? That the only types of unsportsmanlike conduct are those for which examples are given? It's not a violation of the provision that says making the defense think the snap is not imminent by pretending not to be ready is unsportsmanlike. But that's not the only possible unsportsmanlike act!

Fed's provision says, "Examples are, but not limited to:" NCAA's "The Football Code", included in their rules says, "Feigning an injury for any reason is unethical. An injured player must be given full protection under the rules, but feigning injury is dishonest, unsportsmanlike and contrary to the spirit of the rules." NCAA's provision on Unsportsmanlike Acts says, "Specifically prohibited acts and conduct include:", which means there must be nonspecifically prohibited ones too. No code that I know of defines UC in a close-ended manner, but always in an open-ended one, in the understanding that nobody could possibly imagine all the things that might be done in a way that'd be considered unsportsmanlike. It's a technical term that's meant to include the ordinary meaning of the word.