Proctor became the first player in the NRL's 112-year history to be sent off for biting and the Gold Coast forward will face the NRL judiciary on Tuesday night.
Proctor will deny the charge but faces a lengthy suspension if found guilty.
Johnson blew up on field over the incident but then later made up with his New Zealand teammate and said he would not pursue the matter.
Johnson has since taken to social media to reiterate his stance and to "clear the air" on the incident which split the rugby league community.
"Do I believe that Kev had a nibble on my arm? At the time yes I did - otherwise I wouldn't have reacted the way I did," Johnson wrote.
"Since then I have spoken to Kev and he's told me didn't and I believe him. I've also had time to watch the footage - the same footage you've all seen and can see that maybe the force I had against his open mouth with my arm could have been the reason I felt what I did.
"In the heat of the moment I reacted the way I did and I can't change that, no way did I think he would get sent from the field but I did think we'd get something for it. I hate that this has taken attention away from the fact it was Kevs 250th first grade game and what an unreal player he has been for so long for both club and country."
After initially saying he would not take part in Tuesday's hearing, Johnson wrote that he would support Proctor at the judiciary.
"As I believe him being sent off and ultimately costing his team the game is big enough punishment."
Proctor's lawyer Tim Fuller of Gardens law firm told Brisbane's RadioTAB Breakfast Show that he expected Johnson to be present at hearing.
"Kevin is going to be able to produce his defence directly to the judiciary. We are going to utilise some other avenues when it comes to providing evidence around the events," Proctor said.
"The opponent in this particular matter, Shaun Johnson, will be called on to produce his testimony in relation to it.
"It is really an opportunity for all people involved to put forward their version of events and to give the judiciary the best opportunity to make that determination as to whether there actually has been this biting event or not.
"We have got some pretty solid reasons for why we think the judiciary tonight should clear Kevin Proctor of that charge."