The key question is: Was Paul a member of the Sanhedrin?
I am fairly sure that all members of the Sanhedrin had to be married. If that part is true, then look at the evidence to see if he was a member of the Sanhedrin or not.
Acts 7:58 And cast him out of the city, and stoned him: and the witnesses laid down their clothes at a young man's feet, whose name was Saul.
--Why was it Paul that was holding the clothes of Saul after he was stoned? This gesture would indicate that it was Saul that began the proceedings and had authority over them. It would be an indication that his authority would be directly linked to the Sanhedrin or that he was a member of it.
Acts 22:4-5 And I persecuted this way unto the death, binding and delivering into prisons both men and women. As also the high priest doth bear me witness, and all the estate of the elders: from whom also I received letters unto the brethren, and went to Damascus, to bring them which were there bound unto Jerusalem, for to be punished.
The expression "the estate of the elders" refers to the Sanhedrin. It was from them that he received letters of authority. This would indicate that he was in their presence, presumably part of them. His authority to persecute Christians came directly from the Sanhedrin. It seems that he was a part of them.
Acts 22:3 I am verily a man which am a Jew, born in Tarsus, a city in Cilicia, yet brought up in this city at the feet of Gamaliel, and taught according to the perfect manner of the law of the fathers, and was zealous toward God, as ye all are this day.
---He was groomed and educated to be a part of the Sanhedrin. No person in that day could have received a better education than Paul. There was no better or famous teacher than Gamaliel. If you wanted to be among the "in crowd" among the Pharisees, that is where you would go to receive your education. He was taught "according to the 'perfect manner' of the law of the fathers. His education alone would point him toward being a member of the Sanhedrin.
Taking all the evidence above and putting it together, I would say that he definitely was a member of the Sanhedrin, and that being the case was at some time in his life became a widower.
