Peter McClure, 62, is suffering from lung and rectal cancer and has outlived his doctor's prognosis.
McClure says he was told by Service Canada 18 months ago that his condition wasn't severe or prolonged enough to qualify for CPP disability, and was advised to apply for CPP retirement benefits instead, which pay significantly less.
The government's social security tribunal recently expedited McClure's CPP disability appeal, but ultimately told him its hands were tied because he was already receiving retirement benefits.
Provisions in CPP legislation give Poilievre, as minister, special authority to intervene if people have been denied benefits due to erroneous advice.
Weeks after the department was first asked if he'd use that authority — and then insisted upon a waiver signed by McClure in order to speak publicly about his case — a spokesman for Poilievre said that won't be happening.
"The Canada Pension Plan specifies the eligibility requirements for a disability pension," Aaron Bell said in an email. "The minister and the SST are bound by the legislation when determining if a person meets the requirements for a CPP disability pension."
McClure says he's taken aback.
"I don't get it," he said in an interview from Spruce Grove, Alta.
"The law requires the minister to correct mistakes his department has made ... this is his chance to be fair."
NDP MP Jinny Sims, who's been harshly critical of the government's handling of its social security tribunal, called it "cold-hearted and mean" not to intervene to help McClure.
"Here we have someone diagnosed with terminal cancer, and he was obviously mislead and misinformed, and the minister refuses to intervene on humanitarian or compassionate grounds," she said.
"It's not as though Mr. McClure wants the money to go on holiday. It is going to add to the quality of life for a dying man. What planet does this government live on?"
Follow Lee-Anne Goodman on Twitter @leeanne25