When approached for comment yesterday, Mr Penman confirmed he had been driving on an expired licence, but "wasn't aware of it".
"There are probably numerous people out there whose licences have expired and they aren't aware of it."
He had been contacted by police and told to rectify the situation, which he hoped to do this week.
Mr Penman said he stood by his key snatching, which prompted a comment from Prime Minister John Key condemning the practice.
"I have no problem with doing it again. If it saves people's lives I have no problem with it."
Mr Penman admitted last week to taking the keys off another motorist in an earlier incident.
"I've been in a head-on crash before and I don't want to be in another one," he said, adding that he would continue to ignore police advice and keep up his vigilante actions in order to try to keep the roads safe.
Since going public about the latest incident he had received plenty of feedback, he said.
Mr Penman tooted his horn after a rental car stopped on the road while its occupants took photos of scenery, causing eight vehicles to back up behind them.
He later blocked the car from exiting a driveway and snatched the keys from the driver.
Police were called to the scene and spoke to both parties. No tickets were issued.
Mr Penman said other than some online comments, most people were supportive. "Everywhere I have been people say 'good on you' for standing up."
Meanwhile, a Queenstown judge yesterday cleared rental car firms of any blame when tourist drivers who hire their cars cause crashes.
Judge Christina Cook, at the resort's district court, said the onus fell on the driver to assess whether they had the skills to drive on New Zealand roads before hiring a car.
There have been widespread calls for firms to be required by law to test tourist drivers' skills before handing over the keys, following a series of serious crashes.
British couple Paul, 57, and Rosa Whitmell, 54, who were driving from Mt Cook to Te Anau, suffered serious injuries in a head-on collision with Chinese driver Qian Li, 34, on Gibbston Highway on February 21. Li's passenger and friend Mingyue Shen was also injured.
Judge Cook yesterday sentenced Li on three charges of careless driving causing injury, disqualifying her from driving in New Zealand for 10 months.
She was ordered to pay $2500 to each of the Whitmells in emotional harm reparation.
Li's solicitor, Bryce Whiting, made a submission that "serious questions have to be asked whether it is responsible for these people to be given rental cars" to drive on challenging Central Otago roads at speeds they were uncomfortable with.
But Judge Cook dismissed this. "I do not accept the submission from Mr Whiting that rental car companies are at fault in respect of this matter.
"Miss Li, in taking the step of hiring a vehicle and driving in New Zealand should have, before she took that step, been confident to drive in New Zealand conditions and been aware of the challenges of driving on New Zealand roads."
A witness saw Li veer left before overcorrecting sharply to the right, causing her Toyota Corolla rental car to head right, cross the centreline and crash into the front driver's side of the Whitmells' rental car.
Checks on the car's "black box" showed it was travelling at 95km/h, and conditions were fine.
Mr Whiting said Li, of Hangzhou, was used to driving at a maximum of 60km/h on single-way motorways.
Judge Cook said: "I accept that this was not a sustained period of dangerous driving but ... as the charges laid reflect, an error of judgment which had substantial consequences."
Li was also fined $500 on the charge of careless driving causing injury to Miss Shen, with $130 court costs.
