Steve,
I understand now and you have explained your position well and given an excellent example. Where our opinions had differed relates directly to our lines of work. I work in marketing where results are less tangible. I will spend significant time on the phone working with people that are not current prospects for my products. I do this because someday I know that they may be a prospect and people can be influenced the positive experience/conversation that they had.

In reading your post I agree completely that from a shops standpoint you cannot afford to spend significant parts of your day working with customers where there is ZERO prospect of future profitability. It is probably good that you sped the conversation with that individual and made him feel rushed. If I were in your shoes I wouldn't want that guy to refer people to calling me from different parts of the country because I helped him out. I can picture the person you described in fact I work with those types of people every day. It sounds like he was in a position of power in an organization and thought that everyone should listen to his every word. Someone that could take 20 minutes describing how he zips up his pants.

A very important part of business is protecting good customers. Giving them a break here or there can ensure that and it sounds like that is something that you do.