Alert is completely useless against Bastion.
It's true. Since Alert prevent being surprised and nobody can ever be surprised without DM fiat, Alert is useless (except for the bonus to Initiative, in order to blast with AoE spells. In a regular game were surprise is a thing, Alert defeats it.
By RAW, it works like that:
Non-surprised fight sample against a stealthy dispellers (for example, because Wizard is Alert or because Surprised doesn't exist by lack of DM fiat).
BEGINNING OF ROUND
Initiative is rolled, Sorcerer rolls 12, Wizard rolls 14.
Wizard gets initiative and acts on count 14. as he saw nothing, he just readies an action "Teleport away as soon the situation sours." and tells to his Simulacrum to ready an action "Meteor Strike the ground around you whenever an hostile action is taken".
Stealthy dispeller cast dispel magic
Readied actions. Wizard teleport, the whole area is blasted by a meteor swarm, possibly, but not necessarily, including the dispeller, his simulacrum, his DMM... according to the luck of the blasted area selected.
Stealthy dispeller finally dispels the Simulacrum, who turns back to snow.
End of Round.
while, against a surprised wizard it would be:
BEGINNING OF ROUND
Initiative is rolled. Sorcerer rolls 12, Wizard rolls 14.
Wizard gets Initiative, but being Surprised, he can take no action this round.
Stealthy dispeller casts Subtle Polymorph, which the Wizard couldn't affect even with a reaction (because surprise)
End of Round.
Depending on whether the save worked or not, there might a need for a second round, in which case everything is back to normal.