You don't necessarily need to bind his bombs to hurt him as he has a weak spot on top that you can exploit by planting some accurately placed seeds. It's kind of hard to do it at first since his weak spot is pretty narrow, but after a few times you'll know where to aim. Only took me three times of stabbing him with the seeds.
You're kidding... I have to try that. Regular flower seeds, or charged ones?
I had a similar problem as the original poster in that it seemed you had to be so fast to do this that I couldn't possibly manage this fight, but I did. I think the bombs explode earlier if you unbind them. Or perhaps it just takes that many more seconds to unbind and switch forms, that you can't afford to do that. At any rate, binding, switching forms, charging seed... that seems to be manageable often enough that I beat him.
They should have made the reward for this boss be the last memory. Actually, the other two were good accomplishments, so perhaps just get rid of the first memory. I know the game won't be changed. I'm just thinking hypothetically. :>
BTW, why is the memory in the sun temple "2 memories" instead of one? I can't imagine Li forgot, even if it was also his memory. :> Unless Mia wiped his memory of Naija as well, which might explain why he ran away from her.
