The answer to that question is I wouldn't. Nor would I judge another brother for my own personal conviction. If this guy was openly fornicating or blaspheming and dragging Jesus name through the mud that would be different.
"Speak not evil one of another, brethren. He that speaketh evil of his brother, and judgeth his brother, speaketh evil of the law, and judgeth the law: but if thou judge the law, thou art not a doer of the law, but a judge."
We'll, SC from Ohio, do you think the Roman soldier Jesus commended for having great faith had any questionable affiliates.? Don't hear Jesus demanding him to leave his station in life.
God Bless this brother for his willingness to speak for Christ. What's up with impugning his motives? It is up to his conscience whether or not he wants to play in the NFL. "To his own master he rises or falls." "For in many things we offend all."