I think that would work just as well and would have been my first idea too, but IMHO it's kind of an elegant solution to do it this way. The recipient can very easily find the exact version used and they don't have to maintain that information somewhere else. Especially if they add specific patches -> I know that they often modify the game binaries, but maybe they have custom DOSbox changes as well.

They would have to send a written offer valid for any third party and for IIRC 3 years, so they'd have to commit to their hosting being available and so on. Probably cheaper to just send the 1.5MB.