Vyvyan Basterd
Adventurer
I think your claim that you are following RAI isn't accurate at all since we really don't know what RAI is.
I don't claim to know what it is, but I can strongly infer the intent.
Shield is intended to shield you from attacks and should be able to disrupt attacks. "You throw up your hand, and a shield of arcane energy springs into existence, protecting you against imminent attacks."
Bear's Endurance is intended to allow one to endure damage, not avoid attacks altogether. "Drawing on the boundless endurance of a bear, you regain a measure of your vitality."
Regain, not Gain. At best I can see the valid viewpoint of gaining the hitpoints then taking the damage (even though I do not agree with this as I'd rather choose a more beneficial effect for the character), but you cannot convince me that the intent was to gain hit points that would then make you an invalid target for a power.