As Brucklay says, it could just be boyish behaviour.
But I castrated two goats, or at least, I was there when they were done. They were done with a burdizzo (omg, horrible, will never do that again) and it was done thoroughly and properly.
My boys started behaving boy-sterously and when I checked their bits, there seemed to be something there. So I took them to the vets to be done and they still had 3 1/2 between them

You could see the white line in the hair where the clamp had been (on dark goats). And the scar tissue. But they definitely still had apparently functional balls.
And I have ringed a number of shetland lambs last year, still got them here now, some successfully and some not as has become apparent as they've grown up.
So, unless he was surgically castrated by a vet, I wouldn't take for granted that he's 'safe'. I'm sure people are more experienced and successful at doing it than me - but then again, some might not be.