I guess the results are only trustworthy if they're from a state Trump won.

If you were trying to rig the presidential election, would you do it for every state or just the ones pollsters would call "battle ground states"?

If you're trying to argue the claim "I would rig the battleground states, therefore the presidential election in those states was rigged", your claim is flawed for two reasons:

A) It is based on the belief "The Democrats would rig the presidential election", which is completely unprovable. Even if your belief was true, that alone doesn't prove that they did. Speculation is not evidence. If "Alice wants to kill Bob", that doesn't mean that Alice will eventually kill Bob, nor, if Bob ends up murdered, does it prove that Alice did kill Bob.

B) Florida and Ohio are also battleground states that used Dominion machines in the 2020 election, and they were won by Trump. Yet no post-election allegations of voter fraud were raised in those two states.