In his closing submissions, Nicholas Adamson said Shay Ben-Moshe gave "troubling" and "misleading" statement to police following the explosion in a north Toronto neighbourhood in August 2008.
For example, Adamson said, Ben-Moshe told police that a safety audit of the plant had come out "perfectly good" when in fact it initially failed the review.
Sunrise, Ben-Moshe and fellow director Valery Belahov face numerous provincial-offences charges in relation to the blast and fireball that killed an employee, Parminder Saini, 25, and rained damaging debris on the surrounding neighbourhood. A responding firefighter died of a heart attack.
Ben-Moshe's lawyer has blamed the incident on equipment that malfunctioned due to a manufacturing error.
But the government said the blast occurred when propane vapour leaked from a defective hose or pump bypass and ignited during a risky truck-to-truck gas transfer.
Sunrise had been told almost two years earlier to stop the transfers but continued them as a matter of routine, court heard.
Defence lawyer Leo Adler has argued Sunrise was aware of the ban on truck-to-truck transfers but believed it could continue the practice while it built a huge storage tank on its property.
Adamson said there was no evidence to support the suggestion Ben-Moshe somehow had such permission.
He also noted that Sunrise took the better part of two years to put up the tank.
"It shows a lack of diligence on Sunrise's part," he said.
Even if Ben-Moshe honestly believed he somehow had permission to continue with the dangerous transfers, Adamson said, the company took few steps to mitigate the danger.
He said there were no systematic safety inspections or oversight of the drivers doing the transfers. Nor were drivers told the transfers were "presumptively illegal" and got no extra training.
"Appropriate supervision here may have made the difference," the lawyer said.
The company did little by way of preventive maintenance on the pump or hose blamed for the explosion, Adamson said.
He urged the judge to take the director's "self-serving" statements to police with a grain of salt given their "unreliable" nature.
Adamson called it "astonishing" the company's self-described "Mr. Everything" claimed he didn't know where at the plant the daily transfers were happening.
"He seems to be trying to distance himself from that part of the business," Adamson told Ontario court justice Leslie Chapin.
He urged Chapin to reject another defence suggestion that the event was an "act of God," saying this wasn't a natural event.
"A hose and pump are human devices," he said.
The trial, which began in February, was slated to end Thursday, but those involved said at least another day of closing arguments would likely be needed, probably in September.
Sunrise, Ben-Moshe and Belahov face millions of dollars in fines if convicted of violating environmental and labour regulations.