A report on Heavy.com seems to have the info:
The real reason Frank Trigg was dropped from his UFC contract and then quickly undropped? Dana White was furious when he found out Trigg was a part of the upcoming EA Sports MMA video game. White had decreed no one who had signed with EA, in competition with his own UFC games, would ever fight for his promotion.
When he found out about Trigg, White was livid. Cooler heads prevailed, but look for Trigg to get another tough fight. If he loses again, he's gone.