Thanks for the feedback!
The T9K is certainly deadly, but a monster that blows over in a stiff breeze would be anticlimactic. I'm newish to Mothership overall, and haven't quite nailed monster threat levels quite yet. I figured it being able be paralyzed after 2 rounds of riding the bull would be sufficient to end it without a TPK.
As far as the tables go, a d20 is actually not right for the math in order to get the desired outcome here. It's a weighted escalation table, where the longer you play, the more likely you are to get a story result. It keeps the scenario to about 12 encounters total, and you're only likely to see less than half of the results on a given run.