Care to elaborate?
You just woke up. You don't know if the coin was head or tails, and you have no further information. You knew it was 50-50 before going to sleep. No new information, no new answer. I don't see what the "twist" is. Monty Hall, there's another information input - the door the host opens never has the prize behind it.
Or, another perspective : a perfect erasure of someone's memories and restoration of their body to the pre-event state is exactly the same as if the event in question never occurred. So delete the 1 million from consideration. It's just 1 interview post waking. Heads or Tails?
You've woken up. That, itself, is information.
Your latter paragraph, like so many 50/50 justifications, replaces the actual question with a different one.
A friend referred me to another paper on the Sleeping Beauty problem. It comes down on the side of the halfers.
I didn't have the patience to finish it, because I think SB is a pointless argument about what "belief" means. If, instead of asking Sleeping Beauty about her "subjective probability", you asked her to place a bet, or take some action, everyone could agree what the best answer was. That it perplexes people is a sign that they're talking non-sense, using words without agreeing on their meanings.
But, we can make it more obvious what the argument is about by using a trick that works with the Monty Hall problem: Add more doors. By doors I mean days.
The Monty Hall Sleeping Beauty Problem is then:
The halfer position implies that she should still say 1/2 in this scenario.
Does stating it this way make it clearer what the argument is about?