Ruling on AOO

[nycdan]

Or he can take Total Defense (+4 to AC; standard action) and mount the horse (free/move action) and provoke the AoO, but he gets +4 to his AC so... Might be worth the try...

Can't the orc attack the fighter as his standard action and then mount the horse as his move action all in the same round? He would face the AOO if he fails to down the fighter, but this is allowed right?

His alternative would be to use Total Defense as his standard action and then mount as his move action at +4 vs. the AOO.

Is this correct?