Haas will join the Rabbitohs next season after playing his entire career with the Broncos.
It has been reported Maguire received a text from a businessman with links to the Rabbitohs who asked if the Broncos would release Haas before June 30 to join the club immediately.
There is no suggestion he did so with the Rabbitohs' knowledge but Maguire was asked what his thoughts were when the alleged message popped up on his phone.
"No. No chance. Basically Payne has invested everything into this year," Maguire said.
"We'd love a few different results, but Payne has been in everything. He's in my office, he's working hard with the leaders.
"I've got a really good group of men in there here and we've got to get going."
The defending premiers have lost six games in a row and are in 13th position, but Maguire said "this group is well and truly alive" and could still challenge for the finals ahead of Friday night's home clash with the Roosters.
The call to make Haas skipper in the absence of injured captain Adam Reynolds was "an easy decision".
"Just to see what he has done and put the club where it has been," Maguire said.
"He is hungry as. He loves the club and we know he's leaving at the end (of the season), but he also has a massive passion for what the club has done for him."
"I don't look to the future. We are looking at now. We've got a massive opportunity as a club and as a playing group.
"Over time we may have our full complement of players back at the right time, but we've got to get going now."
Maguire said he was confident fullback Reece Walsh could go on a run to the finals like he did last year.
"There's no reason why he can't," he said.
"Reece the last couple of months has put his head down and worked really hard. Those rewards will come.
"It's up to the team to get that going and if they do it for each other, I know I've got one hell of a team."
Versatile veteran Ben Hunt also gets the chance at No.7 in place of Reynolds. Re-signed until the end of 2027, Maguire said Hunt was a team player who would do anything, anytime.
"We all know he loves playing seven, but when I signed Hunty I sat down with him and spoke about what the team might look like in the future. He said, 'Madge, wherever I can play, I'll play'," Maguire said.
"He did that last year, he's doing it this year and now gets the opportunity to play seven."
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