The US has been defending Taiwan since before integrated circuits were invented. Supporting an ally and a democracy in a critical location is the only reason that matters.
That doesn’t matter much to this administration, but it’s not like they’re going to care about TSMC either.
You are so naive to think that US actually cares about democracy. Do you ever wonder why they invaded Iraq two times, but never really bothered to invade Cuba, which is in their backyard? Because Cuba has nothing of value, no natural resources, no valuable technologies. So the US tolerates communist regime in Cuba, because there's no money in invading it.
I will disregard "Bay of Pigs Invasion", since that wasn't really US military operation, but some small scale, CIA orchestrated coup.
That doesn’t matter much to this administration, but it’s not like they’re going to care about TSMC either.