I don’t see that that makes other formulations “not Occam’s razor”, it just makes them less useful attempts at formalizing Occam’s razor. If an alternative formalization was found to work better, it would not be MDL—would MDL cease to be “Occam’s razor”? Or would the new, better formalization “not be Occam’s razor”? Of the latter, by what metric, since the new one “works better”?
For the record, I certainly agree that “space complexity alone” is a poor metric. I just don’t see that it should clearly be excluded entirely. I’m generally happy to exclude it on the grounds of parsimony, but this whole subthread was “How could MWI not be the most reasonable choice...?”
I’ll accept that.