+1 to that comment.
Like you, I make a deliberate decision to go either colour or B&W. In my case it is almost always at the time I take the shot.
I don't have an issue with people critiquing what I have done, including the choice of colour or B&W, but only if they can point out why they are suggesting my creative choices are not working for them. Telling a very experienced photographer "I'd like to see that as a B&W" is not useful.
On the other hand making the suggesting to a relative newcomer and explaining why you are making that suggestion can be a useful by suggesting alternatives to the approach he or she has taken. Antonio is obviously not a beginner...