WB already knows Oden long enough to understand what he's gonna be like i.e., he was hard to control and Oden was exactly that. They had to keep watching him to stop him from doing whatever he wants, and the issue persisted even after he joined Roger. They shared a positive relationship unlike BB and Shiryu, so I can see why you might think they're different and I too am not saying they're literally the same. As I said, BB is wary of Shiryu in his own way. I am not saying they have exactly the same kind of relationship.
P.S.
Also, I don't think BB's talking just about trust issues when he says that.
I mean he's obviously making some kind of comparison b/w Aokiji and Shiryu but we can't know if it's just about the trust issue. Burgess' statement, "But, you see, I can't trust Aokiji!" doesn't go well in line with what BB says if BB was responding to Burgess saying he doesn't trust Aokiji in the first place.
It'd look like,
Burgess: "We can't trust Aokiji!!"
BB: "Zehahahaha, isn't Shiryu the same?"
Burgess: "But, you see, I can't trust Aokiji!!"
As you can see, it seems a bit off so I think BB's talking about something different.