Very odd and corner-case bug. I made a deck specifically to finally 'tuck' a commander in EDH even with the prior rules change.
Indirectly phase out a commander.
I take control of the commander, Turn it into a non-creature (
Soul Sculptor), turn it into an artifact (
Memnarch) and finally an equipment (bludgeon brawl). The card will not equip to anything. I'm not sure if this is too much, or the game still treats it like a creature and cannot attach.
BTW, phase out the creature it's attached to, bludgeon brawl no longer affects the card, it stops being an equipment, detaches and remains phased out. I do this with my other artifacts (like sol ring) they attach, phase out, but remain attached to the creature even though it is no longer an equipment. easily repeatable, I use vanishing as the phasing trigger among other cards. So far, any combination of cards does not produce the correct result.