It doesn't say that they are not entitled to use any OW carrier's lounge only that they have access to the equivalent lounge as to their class of travel. It doesn't state that they have to use the lounge of the carrier with which they are flying

In the lounge access rules in the OW timetable it does go on to say after the sentence regarding Class of travel

"Access is available on the day of departure when your next onward flight is with a oneworld member airline. Access may be restricted at a limited number of third-party-operated lounges or due to capacity constraints. Arrivals Lounges are not part of the oneworld lounge policy."

which to me implies that all OW lounges are accessible still

Dave