>>109073600he was helping himself, he worked for the muties long enough to gather large amounts of genetic info all the while planting seeds to kill off the muties should the need arrive
from what the charts suggests shit really went sideways once he got access to the genetics of the Omegas, once he had the best of the best the muties were worthless to him
and then like
>>109071064 said, the machines took him out before he could fuck them over. Of course Sinister being Sinister he likely has back ups of the data and a clone set up
