Without the full context it's difficult to say. But I add three ideas for whatever they're worth.
1) "Trivial" is a very good thing.
The word trivial has been widely used for many years within the software industry. It means "the solution is so easy it doesn't require any actual work". There is absolutely no insult meant, because it's a happy and fortunate statement of fact.
Very often, the trick with software is to know one esoteric thing that makes an impossible job ridiculously easy. It's like the game of Trivial Pursuit, where that one obscure method makes the whole problem go away. It's no insult to let someone know what that special thing is, because then the person won't struggle too hard to find a solution that already exists. It's like saying "No worries!"
2) The "insult taken" may actually be an ironic joke.
Sort of like saying "Oh, thank me now, but then I'm on the hook to help you all the time. Why do I keep helping people, why, why?"
A. helped B. with a useful bit of computer trivia, and now rues how he may be expected to do all kinds of things to help. One of the unwritten rules of computer programming is "Never let people know how useful you are", because then you'll be swamped with work, demands and expectations!
Being helpful to people may be a double-edged sword.
3) Charity is offensive.
In an entreprenuerial or business situation, nobody does anything for free. There is so much deal-making and favor-swapping that, for many people, doing something for free is unAmerican and just not right.
"If you are a charitarian in reality, could I suggest you help those poor children?"
This sounds like it may be sarcasm directed at how uncharitable person A. really is. It implies that A. is not the type to ever care about children, and that B. resents it -- even while he benefits from A's advice.