In O'Mara's (partial) defense, I will say that the issue of a large, newly-created defense fund is something that O'Mara almost certainly never encountered before.
He knew there was a web site and a fund. It was his responsibility to verify what was in that fund before making representations to the court about finances.
If there was little or no money coming through the web site, knowing that -- and being able to verify that -- would have also been valuable. He had to anticipate that the prosecution would raise questions about the fund in response to any representation about finances.
It's a lawyer's job to anticipate this sort of thing. This is the sort of mistake that a newby lawyer might make -- someone fresh out of law school without a whole lot of courtroom experience -- but anyone with significant trial experience has either had the experience of having testimony blow up when opposing counsel produces documentation... or seen it happen to someone else.
If a client or family member makes a representations about something that can be easily documented -- whether its money, or a statement about where they were at a particular time -- the attorney needs to do his homework and get the documentation in hand before putting that person in the position of giving sworn testimony.
I would find it very difficult to believe that O'Mara or any other experienced lawyer hasn't had a client lie to him in the past, especially when it comes to money.