The Spirit in John 16

I recently have seen some commentary from antitrinitarians about John 16:13, bolded below with the contextual verses. At this point I am neither firmly trinitarian nor antitrinitarian. I am studying.

¹² “I have much more to say to you, more than you can now bear. ¹³ But when he, the Spirit of truth, comes, he will guide you into all the truth. He will not speak on his own; he will speak only what he hears, and he will tell you what is yet to come. ¹⁴ He will glorify me because it is from me that he will receive what he will make known to you. ¹⁵ All that belongs to the Father is mine. That is why I said the Spirit will receive from me what he will make known to you. John 16:14-17, NIV

The KJV translated verse 13 this way:

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 show you things to come. John 16:13 KJV

The KJV leads to the interpretation that the Holy will not speak about himself. However the NIV makes the meaning of "of" clearer. The Holy Spirit will not speak of his own accord. 

The Holy spirit does not speak of his own accord, but what he is given to speak. What is said here echoes what Jesus said in John 12:49-50.

⁴⁹ For I did not speak on my own, but the Father who sent me commanded me to say all that I have spoken. ⁵⁰ I know that his command leads to eternal life. So whatever I say is just what the Father has told me to say.”

It is clear that the Holy Spirit and Jesus both get their messages from someone else, and Jesus says His words are from the Father. It makes sense that the Holy Spirit has the same source for what he says. The Spirit referred to here could be an emanation from the Father and Son, or he could be a third person. The verse is not proof of the existence or nonexistence of a third person, though it is often used to prove the existence of a trinity.

Verses 14 & 15 may be closer to what a trinitarian needs:

¹⁴ He will glorify me because it is from me that he will receive what he will make known to you. ¹⁵ All that belongs to the Father is mine. That is why I said the Spirit will receive from me what he will make known to you. John 16:14-17, NIV

 Those verses seem easy to explain from a trinitarian point of view, but not so easy from an antitrinitarian point of view. I haven't seen any of them trying to explain these two verses.

Further study required.