My guess is, this was a "the VAX guy dropped, the hardware failed, and it was slowing down the project", rather than anything to do with project direction.
I don't personally know him so I really can't authoritatively about what's on his mind. He posted this[0] in Nov. 2015. From my reading of it it sounds like he no longer sees his porting work as fruitful.
sparc? I've heard from a few people that it doesn't run reliably.
sparc64 seems fine however. I run it without a problem.
sgi was miod's baby. Now that he's moved on it may not have long to live.