I would refer you to the talk about "Russia" if you are concerned about disinformation and the integrity of the election.
The Russia investigation, which did not take place during the transition period, had strong evidence (it wasn't a witch hunt), interference was proven (yes actually proven), people were indicted (no not just for process crimes) and resulted in tons of valuable information that is being used to protect future elections (including this one).
If his claims had merit it would be different, but Trump has presented no evidence that he won and he's encouraging the spread of misinformation that only serves to undermine the integrity of the election and country.
We can let the courts decide if a particular lawsuit is "frivolous" or not. Everyone has the right to a vigorous legal team fighting for their rights in court. Putting pressure on law firms because of who they represent is indefensible.
Law firms can also decide if a case is worth it or not. Here's what a federal judge said about a case yesterday in PA:
“This Court has been presented with strained legal arguments without merit and speculative accusations, unpled in the operative complaint and unsupported by evidence, In the United States of America, this cannot justify the disenfranchisement of a single voter, let alone all the voters of its sixth most populated state. Our people, laws, and institutions demand more.”
It wouldn't make sense for any reputable law firm to present a case like this in federal court, there would be immediate damage to their reputation and possibly legitimacy.
Only evidence that they Mueller went after Trump directly with though was in regards to interference though, right? All of this sounds so long ago but it really wasn't, which is an insane thing for all of us to think about. Yes some Trump people were indicted, but there was no ability of the Mueller investigation to prove direct links to Trump in terms of his knowledge or direct approval of what was going on, right? Let me know if I'm misremembering or something here, not trying to change the story or anything, just curious.
In regards to the Law Firms and such, I know that some are going to be under pressure due to representing Trump, though I don't think any clients that they care about are the ones that are angry. Everyone kinda knows that there is a good amount of money even in representing something that is total bullshit and isn't going to go anywhere. Maybe that's just my warped world view on things, but still.