Just because someone is gay doesn't mean they have HIV. For you to assume he is HIV+ just because he is gay is extremely ignorant on your part.
For that to be even REMOTELY possible, he'd have to A. be HIV+, B. cut himself on the glass and actually get blood on it, and C. you'd have to cut yourself on the glass RIGHT after he did.
And they'd have to be deep cuts. Superficial wounds won't do it. Needle transmission is effective because you're injecting the virus directly into your blood stream.
HIV is a lot harder to transmit than you think.
One last question - don't mean to over-post:
Just to clarify, could the blood remain infectious if it got in the cracks of the glass? I'm just thinking of it like a needle.
Also, even if there was no visible cut, pain, or blood, is there a possibility for a microscopic cut that could provide entry?
Nobody in the world ever caught HIV from an event like this. No chance whatsoever. Don't worry and don't get tested.