Last I knew, he was due to meet Garriot as Lord of the Manor backer level and discuss SotA, which I know he is passionate about - he has probably seen the future in that game and lost interest in RunUO, in much the same way players can lose interest in a shard if nothing changes - and Ryan usually doesn't have the time to carry out tasks personally, that's why he hired people like Mark to keep things running smoothly - with Mark no longer around, and no successor to replace him in sight, any ambition Ryan has for RunUO is probably at an all-time low.
I don't think he is letting this place go to waste intentionally, it is probably a case of checking up on it, realising it needs a lot of work, then doubly realising he hasn't the time to do it himself, or find someone to do it and losing motivation - it's easier to hit the X and put it off till next week in that case.
We'd really have to hear it from the man himself though, even though he has made mistakes in the past (we all have), I still don't think he would intentionally neglect RunUO.