Actually law firms have decided to not represent the Trump campaign because of public pressure against these law firms and their other clients.
The pressure campaign to get law firms to drop the Trump Campaign as a client should be condemned in the strongest way possible. Everyone has a right to legal representation.
Representing a client is not an endorsement of their alleged actions or viewpoints. Representing a client is a means to ensure their rights are not violated and that the law is properly enforced.
You'd be right if we were talking about a criminal case. Even the worst murderers deserve a vigorous defense, but these are frivolous lawsuits that the Trump campaign is using as a vehicle to raise money, spread disinformation and undermine the integrity of the election.