Biggest problem is that if he ever builds a second machine it will also have to be 7' tall or else it will make this one look even stranger.
Another suggestion to salvage it is do a big cut out on that back board of the monitor bay, install a vertical LCD there, and have it display something like a Galaga starfield or matrix character waterfall or something.
What I would do however is cut off the marquee box, cut off the correct amount of size from the cabinet sides, route that for t-molding, install that, route the bottom of the marquee box for t-molding too, that way the resulting 2 piece sides will look decent.