Obviously, I hope I didn't give the impression that I was recommending this be a fundamental feature of developing solutions!instead creating default views for relevant cubes using each users preferences through mdx subsets.
As I said, I can hardly ever see a use case for these defaultmembers, and was really referring to self service and not including all dimensions in the view, again not a case I would ever really find useful!
So to summarise, you could use TM1USER in a rule as described, but would you really ever want to? Probably, almost certainly, not.