His comments come following the surprise announcement the 33-year-old will ride for the Cyclingnzshop.com-Biosport team in the Tour of Southland next month.
Landis was stripped of the 2006 Tour de France title after testing positive for banned synthetic testosterone, but he has always maintained his innocence.
"All the guys in prison are innocent too," Henderson said when approached for comment yesterday.
"He is a drug cheat and that should be the opinion of everyone.
"We are all making out he is a big celebrity, but he only won [the Tour de France] and was a good cyclist because he took drugs.
"I heard Gordon McCauley [former Tour of Southland winner and Melbourne Commonwealth Games bronze medallist] say on the news the guy hasn't fired a shot since he has been caught for drugs."
However, Henderson, who is the brother of former world scratch race champion Greg Henderson, said Landis' decision to ride the tour was a coup for the organisers.
"There is certainly going to be a lot more publicity for the tour. Perhaps a bigger name, who hasn't been a cheat, would have been a better idea. But, hey, that might not have got the same media coverage."
Henderson said he would not like to speculate as to how much it would cost to bring Landis out to New Zealand, but added it would not be cheap.
He also wondered whether the rider was over-hyped.
"I know [brother] Greg is trying to get a ride in the tour this year, and he wants the whole family to be paid to come out from Australia. This guy is coming from America and will want appearance money and everything.
"Let's hope the guy wants to come to New Zealand to have a look at our scenery because he won't have seen any thing like it, or the crosswinds or hail or snow in November.
"I think he is in for a shock. We've got some very deep talent over here now. Sam Bewley [Beijing Olympics team pursuit bronze medallist], for example, just signed with Radioshack, Lance Armstrong's team."
Tour of Southland race director Bruce Ross said he was not too concerned about Landis' history.
"To my mind, he has served his time, been cleared to ride again and he will be treated the same as any other bike rider will be treated," he told NZPA.
Cyclingnz.com team manager Wayne Hudson said the decision to approach Landis came about two weeks ago, when one of their original line-up for the Southland tour switched to another team.
"Although we asked a number of local riders to ride for our team, nearly all of them had already committed to other teams for the tour," Hudson said.
He admitted it had been a long shot to ask Landis.
"We thought, `Why not?' All we can do is ask and if we don't ask, we'll never know whether or not he might have said yes."
Hudson said the deal was struck after they were put in contact with Landis' agent, Scott Thompson.
"Floyd had just finished his competitive season, so was in pretty good form and Scott was confident Floyd would rise to the occasion.
"Floyd is the kind of guy who will give his best and turn up every day to ride as hard as he can."
He said sponsors had reacted positively to help offset the cost of flying Landis in.
"We got an almost instant response of `We're in' from two of them."
Landis will be supported by Auckland riders Nico de Jong, Nick Lovegrove and Jeremy Meech, along with Southland triathlete Jamie Whyte, who will all be racing their second Southland tour.
