Let me see if I have the scenario right:
A short stack under the gun goes all in. UTG+1 calls. Both actions are blind - they happened while the dealer was shuffling / dealing. Then something happens that would otherwise be ruled a misdeal.
This seems like a no-brainer. It's a misdeal.
While technically their actions are binding and would otherwise cancel a misdeal, that rule is generally meant for errors discovered after the deal is complete, such as a player with too few/many cards.
In this scenario I seriously doubt any player (other than one who already looked and saw a monster hand) would expect anything other than a misdeal, and would rule it as such.
Technically, the actions were out of turn, since the action was on the dealer to complete the deal before the UTG acts.
Also, the scenario where the dealer forgot to give the button his second card, or accidentally gives the small blind an extra card isn't a misdeal. It gets fixed whether there was action or not.
Or, use the example of casino pit rules that forbid players from touching their cards until after the dealing is complete.
Last, there's good old Rule One.
Bottom line, it's a misdeal.
Note that I would also rule that the blind actions are still binding for the re-deal.