Septy, good for you! and Max. Remember that his sensory glass is full to start. Easy does it, muffle it, dilute it, slow it down, seperate it into parts, whatever it may be.... he can't fit more in until he makes his glass bigger.

Find his comfort zones and join him in them. Some like to be rocked. Swing, hammock, rocker. For me, the, je ne ca pas, was this body work style called Trager. At the end of the session, while face down on a standard massage table, the practitioner put one hand in the middle of my back and one on my rump and gently created a rocking rhythm that went with my shape and gravity (didn't have to push hard) and I'll tell ya, I melted. Go figure. Better than a hot bath!!

When he shorts out, it's not personal. Stay neutral, low key and calm. Aim to quiet on all fronts.....Be prepared to go with his reation, not your intent. This stuff ain't linear, it's limbic. We're kinda feral.( Maybe that could be your special theme song with him :"Wild thing, you make my heart sing, you make everythng groovy....." it doesn't have to be heavy, ya know..)