They are not OUR people... They are sources of temporarily useful information, each associated with a risk and cost of maintainence. They are likely not loyal to us or our interests, and would just as easily compromise our actual agents for a buck... Criminals, terrorist associates, insurgents, greedy traitors... just like the spies in our own ranks. They could additionally easily be double agents, foreign CI plants, providing false information, too risky to keep, outlived their usefulness, etc. ... there are many legitimate reasons to give up sources, what is unusual is that we publically admit it, but I bet there is a good reason.
Way I see it...”the enemy of my enemy is my friend”. If they are indeed helping us, then we owe them some help.
But - Your point about double agents and counterintel plants, however, is well taken.