Your assumption that the courts will rule that bitcoin should be treated like cash rather then a commodity is in my opinion foolishly optimistic. I have no horse in this race (not a MtGox customer). But at the very least this creates huge legal uncertainties for bitcoin.
You make it sound like bitcoin needs to be considered something like legal tender by only mentioning cash. In reality there are quite a few exceptions to this rule (depending on country of course), D&T mentioned a few.
I'm not that interested in how the law is currently interpreted in some specific jurisdiction right now (no horse in the race either), but I would like to see someone actually argue why bitcoin should not have the same exception as these existing exceptions
"to facilitate trade and commerce by favouring security of transactions over the protection of property rights in certain common, but risky, trading situations". Personally I have problems making a good case against that.