Joking aside, I don't really see the problem. If you can't get parts for that machine then it's simply an ugly (or beautiful depending upon your point of view!) mostly empty box taking up a lot of space. At least if you MAME it then it's getting used. And the conversion has been done in a fairly discreet way so in the unlikely event of the parts becoming available it could probably be converted back to a working Computer Space cabinet quite easily.
This is a mass produced fibreglass box we're talking about not a ming dynasty vase!
Wrong wrong wrong! It IS the ming dynasty vase! At least to true arcade historians. (Personally I don't give a crap about some moldy old chineese pottery.) And converting it can do harm if it's a bad conversion. It makes the cab ugly and ruins the cabinet's reputation. See the star wars arm chair for further example. Also as others have stated, converting it robs a true fan of the cab the joy and opportunity or restoring it to it's full glory.
It's people that say "it's just a cab" that make me want to get out my shotgun. How in the world could you enjoy this hobby and not appreciate the artistry of a nice looking arcade cabinet?

?? Especially CS, probably one of the most unique, and therefore, beautiful cabs in arcade history.
People don't mame classics.
Don't mame classics under the guise of "It can't be restored" when you know good and well it could, given enough time, money and tlc.
Don't mame classics to make them look ugly with a non themed, clashing, add-on only to justify it by saying "it can be converted back."
Don't mame classics under the excuse "I can't find/afford a better cab to mame"
Don't mame classics with the justification of: "This artwork is ugly, and therfore, it's not worth saving"
Do not mame them here or there
Do not mame them in a square
Do not mame them no sir-re
Or face the wrath of HowardC
Remember kiddies, just because you don't find something valuable, doesn't mean someone else wouldn't treasure it. There are only so many arcade cabs left in the world so if you buy one for a mame conversion and don't respect it enough to do it the proper way (as in don't make it uglier or hack it up with mods) then please pass that cab on down to someone that will and build a mame cab from scratch.
The "I own it so I can do anything I want" routine does not apply. The louve(spelling?) could, in theory, paint over the Mona Lisa, but that would be an extremely thoughtless and selfish act. An act that would horrify millions of art fans worldwide and deny countless future generations the opportunity to see it first hand. And if you don't feel that strongly about arcade cabs then that's fine, but many are just as rare as a fine painting, so if you don't feel that way then for gods sake don't buy it and trash it.
Ok I'm done..... go back to your business.... nothing to see here..... move it along