Okay, I think I know what happened (sorry for the double post)
For the guys who were wondering about thread 1 and 2.
(Source: Google search results with "Sonic Battle Collab", MikeyTheYoshi's News Entries)
According to the source, Duck Division got hand of a moderators account and started to ban and close random threads. The "Sonic Battle: Collab" was one of them. In addition MikeyTheYoshi got banned for 30 days by [DD], but the ban was removed afterwards from a official moderator.
This happened twice, which is the result of the 3rd "Sonic Battle: Collab" Thread.
Well, what a relief for me. Now I know the reason.
...
Never thought, that they can do more than making those "unbelievable" flash shorts.