jaelis
Oh this is where the title goes?
One concept from an earlier edition of D&D was specific overrides general. If that's the case, the specific of the spell returning at 1 HP should overcome the general rule that HPs can not exceed max HPs.
I think that's a sound argument, but debatable because it is a bit of a tangle of specific and general rules. (For instance, cure wounds can't heal you above your hp max, but that is due to the general rule.)
But for the purpose of this argument, I'm willing to assume that the hp max reduction takes precedence over the spell.