The exceptions may be memecoins, which are more like a casino and are according to a recent study are the category of coins with most chances to move in a "contrarian" sense than Bitcoin and thus could be used for hedging. This means however not that memecoins influence the Bitcoin price either. Only perhaps the Ordinals/Runes based coins could create some demand for Bitcoin but they are already dying and thus their influence may be minimal.
Thus, stricter regulations for altcoins would most likely not affect Bitcoin at all, or only minimally.
Weaker investor protections for ICOs, altcoins, service providers and DeFi, as written above, could even mean a higher crash risk. We've seen with Terra/Luna that a failed altcoin can influence Bitcoin negatively.
However, one would have to wait if this pump can be sustainable. If more countries follow that line and incorporate seized BTC into their reserves or even actively buy some, then this would indeed create a bigger pump. But it's also possible that US and El Salvador could be the only countries following this policy, and then the impact would be again not so overwhelming.
For mass/retail adoption, in contrast, I believe Trump's other announcements about Bitcoin at least are neutral.