A couple of things in your favour....
The MOT and the "removed CEL"
So it if it indeed passed the MOT legitimately "2 weeks ago" then that shows the owner has disguised the faults
If it didn't pass the MOT legitimately well then there is a garage owner with a tightening sphincter right now..
Correct - I'm pretty sure checking that the EML (along with all the other warning lights on the dash) come on is one of the test criteria. So either the MOT centre failed to check it properly/did a dodgy MOT, or the seller was well aware of the light being on, and pulled it after the MOT.