The Titans immediately cut all ties with Proctor on Monday after a now-deleted Instagram story on the forward's own page showed the veteran vaping during his team's loss to Canterbury at CommBank Stadium.

The video was uploaded with the caption "not the halftime vape", with Proctor inhaling and then shaking his head with the Titans down 26-10 at the time.

It's a sad end to Proctor's troubled stint at the Titans, whom he joined in 2017 as a big-name signing after a successful spell with Melbourne.

Proctor was axed as the club co-captain less than a year later after a cocaine scandal while in a New Zealand Test camp in Canberra, and received a four-game ban in 2020 for biting former Kiwis teammate Shaun Johnson.

Off-contract at season's end, the 33-year-old was already set to depart the Titans but that decision was brought forward in the wake of the video emerging.

"Poor KP, he's not the world's worst person. He's a decent guy but it's just a really dumb thing and gave us no choice but to obviously finish him up," Holbrook said.

Last weekend's loss to the Bulldogs was the Titans' eighth in a row, with only for-and-against keeping the club ahead of Wests Tigers and off the bottom of the ladder.

Holbrook said that situation only exacerbated the unacceptable aspect of Proctor's actions.

"It's a terrible look given where we sit the table," Holbrook said.

"People at every club are going to make poor decisions but it highlights the fact when you're not having a good year, that's for sure. It's not good."

Proctor's indiscretion, given his status as a senior player within the squad, has raised concerns about the club's culture but Holbrook was adamant this was an isolated incident and not reflective of a wider issue.

"You've got to react as quick as you can to a bad situation and put a stop to it and that's what we've done but as an overall club ... the nucleus of this side is really committed to the club doing well," he said.

"No-one's happy where we're sitting and an unfortunate action like that, as I said, highlights it and doesn't do us any favours, that's for sure."

Holbrook said he hadn't spoken to Proctor yet but would be remind players of their off-field responsibilities.

"I didn't have everyone here at once today, but yeah, everyone knows what's expected of them," he said.

"You're going to get more scrutinised ... a good example, if you're seen laughing and that where we sit, we look disrespectful.

"If Penrith do it, it's funny because they're winning and that's fact.

"So we're going to accept that and be a little more careful on how we conduct ourselves."

Australian Associated Press