OP so sorry to hear they got your bike, I lost my forever keeper RT 90th Anniversary, car and lots more to a burglary while on holiday. I would end up in prison if I got hold of the scum.
I would imagine it depends on your previous experience of being involved in incidents etc, these little shits are like hyenas, one on one they bark loud but are usually quite pathetic, in a pack they can be a problem. They also have no social line and will stab/attack without fear on consequence.
From some of the stuff I have done (inc employment) I am pretty sure I would get stuck in but under no illusion that I am probably going to get hurt in some form, as everyone does in any physical incident unless it’s a truly uneven match.
Knocking him off the red scooter would would cause the GS rider to heisiate and ponder whether to stop, at this point you have one down and the other one unsure. If you are quick that gives you the upper hand but don’t concentrate on one or you’ll get jumped. A push into the GS with ththe scooter would probably result in both going down and I would guess they would both go for the scooter as a GS is hard to pick up when you are attacking. Hopefully some others will have join you by then.
A good tip, a helmet is a good weapon to headbutt with however the minute you can grab the chin bar and drag it backwards, you have taken control of the head, they will have to go where you pull. If the strap is undone, then you’ve just gained a weapon to keep hold of and hit with. Odds on for human nature, he will try to get the helmet back. This all gains time for further intervention, causes them more issues and adds to their unease.
Just be very careful and know that you might get hurt in some form however if society stood up together these little shits would be screwed.
Just my opinion, I HATE these little shits and would quite happily go toe to toe with them whatever it may bring.