Kuma sending Brook to Laboon would be the same thing as Aokiji helping Tonjit to find his people, except that in Kuma's case would be more like stupid than awesome.
Plus Kuma's a pirate known for doing every crime known in piratecy. Hell, I wouldn't be surpised if he also commited Crewmate murder like Blackbeard.
I actually don't see any reasons for Kuma Helping Brooke. I doubt that Kuma would be in TB in the first place if it wasn't for his stuff of following orders of the WG unlike the other schichibukai.