You're right, I guess it depends on what you choose A and B to be. For:

A = OP supports Mozilla making money from address bar ads

B = Mozilla is honest about making money from address bar ads

"B -> A" (OP supports Mozilla if Mozilla acts a certain way) makes sense. "A -> B" sounds confusing in a sentence, but its contrapositive, "!B -> !A", also makes sense.

However, for:

B = Mozilla decides to make money from address bar ads and is honest about reasons

"A -> B" no longer makes sense, since OP can support Mozilla having the address bar ads with an honest justification, but Mozilla can still decide to not have the address bar ads.