In New York, the answer is "NO". Provided the employer has four or more employees, the interviewee cannot be asked about sexual orientation, marital status, disability, and a host of other things. And any cute attempts to get around it (like the "can I set you up with my granddaughter" reference below)will surely be viewed as an improper question if the interviewee does not get the job, is qualified, and sues.
What state rules apply at the NFL Combine I do not know. I am really surprised Roger Goodell is even allowing this story to get any traction at all. He needs to get in gear a set of rules with related fines to discourage this before it gets out of hand. It is only a matter of time until it does.
Yet another phenomenon that Manti's situation has shed light on.