Talk with the company's benefit "expert." Sometimes they really are knowledgeable. If not, they'll usually tell you.
As I understand the rule, an employee aged 55 or older that ends employment with a company can access their 401k with that company without penalty -- if the company plan permits. This account can be accessed at any time after reaching 55 and after leaving the company. All withdrawals are fully taxable.
You stated it was a "defined contribution money purchase pension plan." I am not sure if the 401k rules apply. Ask the company's benefit expert.
The object of life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane -- Marcus Aurelius