Martin, 21, has been at the centre of rumours on Twitter and internet forums suggesting he one of the players under investigation by the Australian Crime Commission and that this, along with his off-field behaviour have led to him being on the outer at the club.
Hardwick said social media was "un-Australian" amid the swirling stories, and there was no truth to the suggestion the Tigers were about to sack Martin – a rumour he said he first heard six weeks ago.
"He's fine. It's disappointing; social media – it's un-Australian. It's just whinging, whining … I can't stand it," Hardwick said on Friday.
"He's a resilient individual but all we can only deal in, is the facts; he's training very, very well and we're pleased with the way he's going.
"You only have to look at his form against the All Stars last week. His disposal probably wasn't to the level we expect but he was one of our better players."
Martin had a slow start against the Indigenous All Stars on Friday night in Alice Springs but got going in the second quarter, and gathered plenty of the ball across half back.
He was suited up to play in the Tigers' intra-club match at Punt Road on Friday morning.
Hardwick said Martin's form on the track over the summer had been promising.
"He's training very, very well and he's going to be a very, very good player for us this year."
Jennifer Phelan is a reporter for AFL Media. Follow her on Twitter @AFL_JenPhelan.
