If the impeachment managers did this stuff (fake the evidence such as videos, tweets, etc) in a real court, they would face serious consequences.
The Chief Justice recognized it as a sham and did not participate, and one does not need to like Trump to know what this second round was.
The first one was atleast done by the book...
https://news.ycombinator.com/newsguidelines.html
Everyone is biased, so it would be far more productive to just refute the central point, which in the case of mrzimmerman's comments on this thread (as you may realize) is rather straightforward[1] to do.
http://www.paulgraham.com/disagree.html
[1] For example, https://news.ycombinator.com/item?id=26198380
We all have biases, and yes, it is obvious without me alluding to it.
I have stated the facts that counter zimmerman's note
https://www.msn.com/en-us/news/politics/fact-check-yes-mccon...
Which, if you paid attention to the trial was extremely well reported, so either you genuinely didn't pay attention at all or you're trying to imply anyone in Congress seriously believed he wasn't culpable.
So to answer your question simply, he wasn't convicted because it wasn't politically expedient to the rest of his political party.