We can't imply Teach let the hound drop to the ground on purpose. The glove, possibly and simply, slipped off of the hound's hand
It's also risky to think Teach come across as a psychopath. He genuinely feels remorse and sadness over what happened. And those emotions he felt aren't shallow or driven by self-interest.
The only reasons he can be deemed as suspicious are only his memory lost and the instances where he blanked out (like when he almost chopped his hand off).

I really do feel like Teach is also a psychopath or i mean he's not really that innocent, like wdym you didn't notice the man you're holding fell off?
Also another pre introduction of another hound.. Though why is she holding Guwon like that? Girl....