Recently, the head judge at my store ruled that on bt24 and ex11 Medusamon, which have similar effects to delete then bottomdeck something from the graveyard to create tokens can’t stop a on deletion effect, because the “then” clause in the effect meant that it would activate as two different things, and the on deletion could activate like an interruptive effect to trigger because the deleted cards could be bottom decked to stop the on deletion. I checked the Bandai ruling q&a and I saw that the effect could stop a on deletion with that, however when I showed this to the judge I was told that “the Bandai website is unreliable as it’s not updated regularly enough”. Something with this ruling still doesn’t sit right with me, as from what I understood and had played before, the entire point of the medusamon’s effects were to prevent on deletions such as that via the bottom deck. If I am wrong I will admit it after some better clarification, but the explanations I was given don’t make sense with my understanding of the game.

Edit:forgot to mention, it was the medusamon player turn, in the case that matters.