1)So far, any game that Epic was given for free was *introduced* to the store at the time of giveaway. Meaning, you couldn't bought For the King before the actual giveaway.
I'm not sure how bulletproof is my first argument.
There were some games offered twice, like Celeste ane The Messenger.
But since we don't know the ins and outs, it maybe very close to "bulletproof"
What I wanted to say is Celeste and Messenger both came to the Epic store at 100% discount. Other than those two and few more games that were free at least twice, I wouldn't know any "Here's free game, it's first time free, and so short after we sold it at any price", kind of situation.
I have to admit I regularly check Epic store, and I'm so far happy not to spend money there, and during the weekly giveaways,I checked free games, but I can't say i didn't overlooked something.