I stuffed some AV definitions into the testnet chain years ago and _no one_ has ever reported an AV hit on it. Obviously we can obscure the blockchain from things like that, but so far there appears to be no reason to do so.

Do you actually have evidence of some AV software noticing signatures inside the blockchain files?

AFAICT you don't. Even if it were to occur only a fraction of bitcoin nodes run on windows/mac systems with that kind of nutty AV software, so we could simply deploy an update which obfuscated the block files if it ever were an issue. You should take more care with your claims of doom, chicken little.