Yes, but only if you are playing it historically and totally realistically. Attacking the convoy revealed that there was a sub there, and that may compromise the agents you drop off, so in theory you should have not attacked it. But, if you take the view that your objective ultimately is to win the war, then I suppose attacking the convoy was fair enough. So on the other hand, if you regard yourself as the man best placed to make an intelligent choice at the time, in theory you should go for it if you deem it imortant. This is of course what happens in the movie Run Silent, Run Deep, where Clark Gable's character goes against orders based on intelligence he determines from his drills and deductions.
Not sure if the sim's AI is complex enough to make career/renown decisions on judgement calls like that though, so if you get away with it, then you were right! I think I'd have attacked them too by the way.
Chock