The only reason you think it´s metagaming is because you felt the need to state the details of your upcoming attack. I would have done the exact same thing in that kind of situation regardless of Ysolda channeling or not. I quickly discovered how the giant mecha sucks ass against smaller, faster opponents when Erde came over, and I´m still counting myself lucky that he started off in a position that put him in an airborne disadvantage (because of the tail) - If Erde was on the ground, he would have fucked my shit up and LeeRoy knows it. The mecha has a pretty poor design in terms of high-tier ombat prowess, to be honest.

So when Ysolda reached the mecha, my options really only came down to one. Bail the mecha and blow it, continuing the fight with the jet if I had to (removing the speed disadvantage), because there is no way the mecha can harm Ysolda in it´s current position unless it blows up. I made a call. Now, if Beta hadn´t gone out of his way to describe his attack ahead of time, I wouldn´t be having that problem. Was it metagaming? Hell no. I don´t do that.