Why did you leave out the details of the story? It wasn't just "a guy at a skeptic event asked her out." Other important details:
- it was 4:00 am and she had announced that she was tired and going to bed. IOW, anyone paying attention would have realized that an advance would have been unwanted.
- they had been out at the bar (so potentially, she was visibly drunk). IOW, she may have felt - or been - especially vulnerable.
- the guy followed her and waited until she was alone and wouldn't be able to immediately leave to "ask her out." IOW, he made choices to increase her vulnerability.
Definitely creepy, unwelcome behaviour.
Not any circumstance, but if you don't have good reason to think the woman's answer will be "yes," then you ought to know that there's a good chance that the advance will be unwelcome.
And when a woman is:
1) in a vulnerable position (e.g. she's alone, tipsy or both), or
2) has already indicated that isn't interested in doing what you want to do with her,
... then no, you definitely shouldn't ask her back to your hotel room for "coffee."