there are no aikido mma fighters, because ....
1. small joint manipulation isn't allowed, so the main tools of wrist locks not allowed.
grabbing someones moving hand is very hard anyway, a lot easier if they are grabbing your clothing. (no clothing in mma....)
2. only a 1/3 of training in akido is unarmed, the rest of the training is using staff and sword.
hence all of the obsession about wrist locks, the whole thing is based about weapons, not losing your weapon, taking a weapon from an opponent.
Even all the strikes and strike defences, copy the movement of weapon blows, hence all the weird chopping hand attacks, which bear little resemblance to any standard punches. even the throws are based around you holding a weapon, when performing them.
if MMA had swords or staffs, then aikido would be legit.
is Steven Segal legit, no clue.... but at the moment he doesn't look very healthy....