Both sides are in disagreement over whether the impeachment is constitutional or not. However, they can't both be right, so surely the constitution can't be black and white, and there is room for interpretation? Which sort of defeats the point of even having a constitution, if both sides can find evidence within it to support their case.
This might be a completely inane comment, and I'm really just thinking out loud, but I'm wondering why there's even a question of this. Either the impeachment is constitutional or it isn't, there shouldn't be room to argue about it.