They really did dig themselves down a hole when they made Mauga.
Mauga can never be balanced. He will always either be too weak or too strong. That’s the biggest problem with him being focused on sustain.
He’s a huge lump of meat that needs to deal damage to survive with his easy to use weapons. Make his weapons too easy to hit, he’s getting too much sustain. Make his sustain better, he’s getting too much sustain. Take away anything, he’s now suddenly too weak because he lacks sustain and dies very easily.
I don’t think they will easily find a common ground with him where everyone will look at Mauga and feel like he’s on the right spot, not unless the entire game changes around him.