There are a couple of circumstances where one is suppose to assume that a work permit is automatically invalidated (primarily, when once receives PR, all temporary documents are considered as being cancelled at that point in time).
However, I personally have had multiple valid work permits before. (These were all employer specific - and for different employers, but the validity range overlapped.)
Even if IRCC cancels your friend's old work permit, they probably wouldn't do so until the new open work permit based on refugee or refugee claimant status is granted. Thus what the senior forum member said is correct - your friend can work until 2027 or a decision is made.
Also, it's technically possible to have multiple statuses at once. For example, it's possible to work full-time on an LMIA employer-specific (or closed) work permit but also get permission from IRCC to study and thus also hold a study permit. Thus the fact that your friend might technically end up with multiple statuses (temporary worker and refugee claimant) at the same time isn't an issue. (In fact, even after obtaining PR, a refugee/protected person still retains this status in Canada - which can cause problems down the line; mainly if one needs to visit the home country for some reason after obtaining PR.)
My guess would be that the friend arrived a short time ago, and since it's an open work permit I'm guessing this is through IEC or some similar working holiday programme. Finally I'd speculate that the programme was the excuse to get a visa to enter Canada successfully, and then a refugee claim was made right away upon meeting CBSA at the airport.
I don't disagree but I think would be helpful to recount the specific reasoning for this. I'll start though by noting that with the change of PMs last year, the push has been to cut down on immigration to "healthy levels" (whatever that means), meaning that someone who has a valid path to staying in Canada by first starting as a temporary worker or a foreign worker could perhaps get more scrutiny for trying to make a refugee claim.
I would add that some of the guesses I made above were to put the OP's friend in the best possible position in terms of the actual refugee claim. (In other words, I'm being wildly optimistic.)