I wouldn’t call them trump defenders, but rather impeachment opponents. Let’s start there.
opponents to impeachment have been pretty consistent.
1) there is enough reason to warrant an investigation into the Biden’s - obviously.
2) the DNC server was the centerpiece of the Russian collusion narrative, and there’s a possibility that the server, which was never investigated by the FBI, is in the Ukraine. If so, we should get out hands on it and run our own investigation
3) these actions are perfectly permissible and actually expected by the president Reverse the letters at the end of all the names and we’d all say the same thing.