I'm gonna take a stab at the basis for this ship.

While Deku was getting ready for his fight (thus not in the bleachers with Class 1-A), everyone was harping on Bakugou for going all out on Ochako, not going easy on her, some calling her 'frail'. Bakugou joins the bleachers while Deku continues his next match and Ochako calls her parents. They continue the harping on Bakugou.

Bakugou whispers "what part of her is frail?" which shows that Bakugou acknowledges her strength.

I'm caught up with the manga and gone thru both seasons of the show twice.

Still don't get this ship.

Treasure Planet is a kick ass movie tho so I'll take the reference.