I didn't realize the Doctor and Heero are power buddies! Heero's is technically Enhanced Regeneration, but they do pretty similar things. It seemed prudent given his penchant for blowing himself up.

But also hi! I have a teenager. With hilarious 'I have a history with people named Doctor. the last one did things to my genetics and bossed me around a lot' shenanigans which is honestly kind of amusing considering.

"I'm the Doctor!"
"Which one?"
"The Doctor!"
"That doesn't narrow it down."

Queue Heero debating if this Doctor can make him a mobile suit then. All the other ones could.

(Coincidentally Heero's pretty handy around tech as well. So it works for a variety of reasons.)