I'll be honest, that was almost entirely facetious.
I mainly don't like the replacement, with an immediate distaste for it that isn't strictly rational. But here's my current entirely subjective best effort at pinning down why.
I mean, the idea alone that you have to go back and "fix" this thing so that it's cool enough to bring back, rather than just leaving it be this quirky inherited bit, is silly enough. The original is forced in order to spell MASK, but coming up with any new backronym is still conforming to the need to spell that word, so at most it'd be a lateral move. Just lampshade it and move on, maybe.
Mobile, armored, "strike c/kommand" - strong words that hearken to a military squad or strike force with special equipment (masks that are actually helmets) and vehicles (so they're mobile) in particular. The original's main flaw is kludging the spelling of Command so it fits.
Mechanically-advanced, secret knights - the first, compound word is too broad to speak to the specific brand or identity of this group, and can just as easily describe a theme park animatronic or a Rube Goldberg machine. "Secret" just about works; I don't think their agent work was public, since they had day jobs and ducked out to do MASK stuff. So it applies.
And Knights, well. I like knights as an aesthetic and it's a cool word, and "Mobile Armored Strike Knights" is perhaps a decent compromise, if only just to avoid the "Xtreme Kool Letterz" raps. But "Secret Knights" doesn't really click for me with MASK; the sudden swerve into metaphor seems like an attempt to make the first half of the name seem cooler than it is.
But all that's just me, and I'm the sort of weirdo who puts a bit of effort into working "aardvark" into a backronym.