Because you gotta have a Blaster when you have Straxus. I'd recommend the Action Master Blaster. This makes him smaller than Straxus which would give Straxus a large, powerful, overbearing appearance in comparison. AM Blaster is also pretty accurate to the comics and he doesn't need to transform either.
I wish Straxus was at least a voyager so he'd look good with CHUG Blaster after he gets his head upgrade ... I'll still be doing that, though...