shouldn't Ninetales MEG (020/132) 's Supernatural Shapshifter bypass supporters with use clauses?

Hello I've recently tested the interaction between Ninetales MEG (020/132) 's attack Supernatural Shapeshifter discarding cards such as Acerola's Mischief, Morty's Conviction, Cassiopeia and Team Rocket's Archer which share a trait of a use clause ie. "you can use this card only if/when …" this means the supporter card can't be played unless a specific condition is met, but when discarded by Supernatural Shapeshifter the effect should be used as the attack's effect, the attack however can't be the last card in your hand such as for Cassiopeia and you wouldn't be using using the supporter card but rather accessing it's effect through the attack's effect so despite being in a situation where you'd be unable to play said supporter card, as stated in the mega evolution [Edited by Mod_Bee - Only official Pokémon URLs are allowed on the forums] you can actually use the supporter's effect.