If I remember correctly he was around 20k after fighting the big one, then burned down to 11k to kill small oneWas he anywhere near level 44000 before this fight? Kind of funny to burn levels and then end up like, 2x where you were before.
Although it'd also be funny if he was accidentally exploiting the semi-typical game behavior where you get more exp for killing bosses at low levels, so when he burns his EXP, he ends up much lower level than he's supposed to be, exponentially boosting his exp gained to levels it should've never gotten to, slingshotting him past where he was.