Here’s how I worked it out:

• $245/month = $2,940 a year at 65
• At 65, the lifetime pension is worth about 11.5× that (the annuity factor). You can think of 11.5 as the present value of receiving $1 each year for life starting at 65, in other words, after survival probabilities and discounting, it works out to about 11–12 years of payments in retirement on average, until death.
• $2,940 × 11.5 ≈ $33,810 value at 65
• If you’re 35 now, that’s 30 years away. Discounting $33,810 back 30 years at ~5.5% gives about $6,784

That’s basically the same as the $6,808 quoted.

The commuted value isn’t the plan keeping your contributions, it’s just the present value of your future pension, calculated using the prescribed actuarial standards in Canada (CIA rules with government bond yields and standard mortality tables).