Ok, that was important to understand.
I do think dh has a point in thinking that DS does need to have a long term aim of understanding that scratching, kicking and pinching is not on. However obviously disagree with the way he is going about it.
He wants DS to self regulate in the face of he (DH) ignoring the escalating behaviours? And ignoring the need DS is trying to express? But today that didn't work for either of them. DH ended up getting dysregulated and frustrated as well. That's unhelpful. DS needs co-regulation at the minute once he has started to use these sorts of acts with others. Use predictable language, ideally same at home and school. "Pinching is finished. No pinching. It hurts me." Use when/then constructions "when you have calm hands, then I will help you"
On the other hand, bubbles and singing shouldn't really follow behaviour that is tricky to manage or it can accidentally become a reinforcer in itself (I want bubbles and singing with mummy; the way to get that is to pinch a few people).
Best thing is to head this kind of behaviour off at the pass by analysing where and when it happens. For example, was DS seeking connection with DH and getting ignored because he was gaming? Where did it go wrong? Could DH have put the controller down when DS gave early warning signs and headed the whole situation off by interacting with him at that moment? Was DS hungry? Bored? Can he choose from cue cards for example? Can he learn to ask for help? And then what he needs help with via cueing? You need help, DS? What help? Help with watching TV? Help with getting food? You might be able to have pictures home and school that you use in each space that might support communication.
Try to work out with DH what DS's early "tells" are that he is heading towards losing it. Agree that you will work together on a plan to head DS off by responding as consistently as you possibly can to the early tells and therefore preventing the pinching, scratching. This is a kind of middle path - you are working towards a change for DS, but not at a level beyond his ability to regulate (DH's current plan) and not just distracting him (your current plan) but something that attempts to analyze where and when the risks arise, and what that behaviour is expressing, and what DS really needs when he gets like that, and how he might communicate that instead.