Is Nick gay/bisexual?

In chapter 2, he goes down the elevator with Mr McKee:

'Come to lunch some day,' he suggested, as we groaned down the elevator.
'Where?'
'Anywhere.'
'Keep your hands off the lever,' snapped the elevator boy.
'I beg your pardon,' said Mr McKee with dignity, 'I didn't know I was touching it.'
'All right,' I agreed, 'I'll be glad to.'
...I was standing beside his bed and he was sitting up between the sheets, clad in his underwear, with a great portfolio in his hands.
'Beauty and the Beast...Loneliness...Old Grocery Horse...Brook'n Bridge...'
Then I was lying half asleep in the lower level of the Pennsylvania Station, staring at the morning Tribune, and waiting for the four o'clock train.

Is that small passage enough to make a conclusion? Perhaps what Nick is really attracted to in Jordan Baker is her masculinity - she's described as being quite butch. What do you think?