Brendan Barry, who runs Outside Obie in the Auckland suburb of Mount Eden, said Samsudeen was with two or three others who visited occasionally to play the pokies.
On one occasion Samsudeen had been waiting outside, but appeared to have got impatient and came in.
"As he's come in, I greeted him and his response was to look at me like I was dirt, so the animosity between us was instant," he said.
"I can't remember really what he said or if I said anything to him, but it was obviously enough to draw attention because his friends in the pokie room came out instantly, and took him away basically. I said something like 'you can't be here if you're racist towards white people'."
He said Samsudeen's hatred for him was clear, and his friend returned to talk to Barry afterwards.
"He said 'don't mess with him, you know, he wants to do a lone wolf attack'. And he told me that he [Samsudeen] wants to go and stab people. So I was like, I need to call the police and do something, and he said that he's already been to jail and the police are following him.
"At one point I said 'tell him to come here for his lone wolf attack' meaning I'd take him on. And that's when he said, 'No you don't understand - he wants to kill a woman, he wants to stab women. For him, the western woman represents the devil and evil'."
Following the news of what had happened at Countdown, he said he had a hunch he knew the attacker.
"Then as soon as I saw the picture, it was like 'yes, that was that guy'," he said. "Afterwards I was fairly well disgusted in the response, particularly in the media. I thought they didn't ask the right questions.
"This idea that we can't cancel his visa because he might get hurt. Why not let him go? Stopping him leaving because he might join Isis. Let him go. Those all don't make sense to me. We should have had a responsibility to the people of this country first and deported him, at the very least let him go."
He also criticised the decision to take down Samsudeen's Facebook page, which he said potentially prevented authorities being alerted to his plans and thwarting the attack.
When Samsudeen appeared at the High Court in 2020, Justice Downs warned that New Zealand was not immune to lone wolf attacks.
The Crown had wanted to charge Samsudeen under the Terrorism Suppression Act, alleging he was planning to carry out a terrorist act.
In his decision, Justice Downs said: "Terrorism is a great evil. 'Lone wolf' terrorist attacks with knives and other makeshift weapons, such as cars or trucks, are far from unheard of.
"Recent events in Christchurch demonstrate New Zealand should not be complacent. Some among us are prepared to use lethal violence for ideological, political or religious causes."
Legislation passed in the wake of last year's supermarket attack has made preparing a terrorist act a criminal offence.
