Maybe get another helmet and let him watch.
That is my thought process also. He might want to do it once he sees it. Can’t tell you how many youngsters I’ve taught to weld because I have extra helmets and they thought it was the coolest (just like I did).
When my daughter started walking, she wanted to climb the stairs. We told her get mommy or daddy and you can climb all you want. Just don’t climb by yourself. So she would get me, and I’d stay with her, let her climb to the top and I’d carry back down and let her climb to the top and repeat. It wasn’t a taboo thing to climb steps, once she could climb and get down on her own, we still want to be with her, but it significantly reduced the danger.
I’d rather see him be with you in the shop and interested in what pa-paw is doing than sitting and watching tv all day.