I don't really know exactly why people are moving, because they fired who? and why did this person got fired?
Anyway, Reddit always sucked. I never liked the layout. I hated clicking on a "thread" and being directed to a link instead of opening up like on regular forums. The only thing I liked is the easy of creating a new account without any confirmation bullshits.
I guess is most likely a part of the community support a few individuals where putting into Reddit, now having a competitor they most likely want to make a statement that their management is far behind in things and the community response is switching.