The important thing is that he maintains tempo. Most people with com morph builds try to morph it all the way before engaging, giving opponents a very large window to abuse. If you're going to turn your com into a strider, you may as well just build a strider, which is more efficient.

What Raaar does is he utilises the com immediately, maintaining high pressure while only building the most crucial support units from his factory. Because morphing converts your metal into an immediate field advantage, he has a big power spike every time his com completes a morph, at which point he's almost certainly got local superiority and can push.

He does let his opponent out expand him, and this is problematic in 1v1, though pretty irrelevant in teams. Unlike late game coms though, he's in a position to punish greed before it pays off.

I also like his mix of modules and units. His compositions are always interesting and effective. I haven't played the game he's working on, but he mentioned there was a large focus on commanders, so I imagine he's sort of scaffolding and/or experimenting.