Goku notices the incoming firebird/dinosaur fight and flies off and around them. Too close to really attack them from there. But, now's not the time to hold back as others are in danger.

He takes notice of the rain of feathers heading for Lan Wangji and Lea and decided to give them a hand, launching a massive burst of ki at the feathers to destroy them if possible (if not, certainly scattering them away)