You did the right thing and avoided unpleasant repercussions. But as cnimrod, berettaprofessor, Edward429451 suggested, the next step might be to contact their parents (or wait until the next time you see them), and suggest a "firearm safety introduction" that includes holding the rifle.
If you mention "The Four Rules" one of the adults is going to ask what those might be - that's your opening. Explain, and point out that demystifying is one of the best ways to satisfy curiosity - their sons are less likely to do something stupid later in their childhood years if they get some reality now. If the parents are liberals, you mention that people need sound information to properly make their own informed choices - can't argue with that.
If the parents go for it and the kids come for the lecture and seem to have a clue what it is about, you now have an opening to suggest a range trip with a .22 rifle for an introduction to marksmanship - single load, single fire, "just like the prone slow fire stage in the National Matches", spoken to give an aura of safety/control, and "respectability".
I'm sorry to babble like this but 1) I'm an old man with no kids to teach and envy your chance to get a couple of youngsters interested in shooting, and 2) it has given me great pleasure to watch a couple of our Junior shooters - specifically two teenage girls whose parents drive them to the matches - climb from Marksman to Sharpshooter and Expert, and one on to Master!
The shooting sports, and the ideas of self-reliance and independent responsible action, are not going to die out if we encourage and support these kids.