Err no, Bolt - tested to a much higher standard than any MMA athlete for the last 10 years so you'd be more confident that he's clean than any MMA athlete. How many MMA fighters are blood tested?
Any sprinter who has been completing since Beijing and hasn't been caught is probably clean, you'd be far more confident that they were than you would of any MMA fighter who's been active over that period, including Roy Nelson. The USADA style testing has been used in Athletics since 1989 and they've been testing blood since 2001.
If USADA had blood tests for MMA athletes going back to 2008 and retested them the number of no contests would be ridiculous.