This is exactly the nuance that most guys miss. When women state their comments about nice guys it is a rhetorical ah .... sure you "are" a nice guy (but you really aren't).
The most one should expect from doing nice things which you should do for others is friendship and the possibility of future communication and nothing more.
I have actually had this happen to me in my travels. I was sitting an airport lounge bar drinking my drink. A guy went off and was very vocal but had a professional edge. I bought him a drink (actually had his drink refilled) to be nice.
He was gay, and assumed it was a pickup line.
It wasn't and even though I am pansexual now (that I unwound all of my trauma and personal issues to work through it). I was not sexually interested.
So that experience taught me a view from the team woman viewpoint ...