If they get back to you in a couple of days, that shows good manners and correct behaviour. Pay attention to them, and be polite.
If they get back to you in two months, you have a gained valuable information. You can be careful in the future…but you need not be all that polite – just civil.
If they never get back to you…they got back to you. Also valuable information. You need not be careful any more, though – in fact you need not worry at all about them, or their lives, or their requests. They got back to you.