I'm still convinced All For One orchestrated the death of the Shimuras and gave Tenko his decay quirk.
You're tell me this child is:
emotionally vulnerable
related to a recently defeated enemy
related to a family member of said enemy who was abandoned specifically because of a pattern of attacks on OFA user's family members
such a late bloomer he's suspected of being quirkless
developing a mutation quirk that's supposedly not in the family line
developing a quirk that is so dangerous it kills six people and destroys an entire house the moment it activates
Yeah that all seems like a perfectly reasonable coincidence. The guy collecting quirks like pokemon cards just had an amazing stroke of luck finding a successor and did not creep into a child's bedroom to give them a life-ruining quirk while they were sleeping.