It makes more sense for the comforter Whom Jesus spoke to be a man.
Jesus was a Comforter because Jesus brought the Holy Spirit. Muhammad was another Comforter and He was also the Spirit of truth.
John 14:16 And I will pray the Father, and he shall give you another Comforter, that he may abide with you for ever;
John 14:17 Even the Spirit of truth; whom the world cannot receive, because it seeth him not, neither knoweth him: but ye know him; for he dwelleth with you, and shall be in you.
It makes no sense that the Comforter is a disembodied Holy Spirit because a disembodied Holy Spirit cannot do the things mentioned in the following verses.
John 14:26 But the Comforter, which is the Holy Ghost, whom the Father will send in my name, he shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you.
John 15:26 But when the Comforter is come, whom I will send unto you from the Father, even the Spirit of truth, which proceedeth from the Father, he shall testify of me:
John 16:8 And when he is come, he will reprove the world of sin, and of righteousness, and of judgment:
John 16:13-14 Howbeit when he, the Spirit of truth, is come, he will guide you into all truth: for he shall not speak of himself; but whatsoever he shall hear, that shall he speak: and he will shew you things to come. He shall glorify me: for he shall receive of mine, and shall shew it unto you.
Muhammad did all these things as Jesus promised He would. We taught that it is not enough to follow Him but all the prophets who have gone before Him.
Say: "We believe in Allah, and in what has been revealed to us and what was revealed to Abraham, Isma'il, Isaac, Jacob, and the Tribes, and in (the Books) given to Moses, Jesus, and the prophets, from their Lord: We make no distinction between one and another among them, and to Allah do we bow our will (in Islam)."
Quran 3:84
The argument about Jesus being a sinner is the same argument the Jews used about Christ breaking the Sabbath. However both Muhammad and Jesus had the authority from God to bring new laws, reinterpret the existing ones and dispense with those that were no longer relevant.