The quote from BAEC is "funny". I'm sure Finnair told BAEC that, but as far as I can tell, Finnair isn't really prioritising their own frequent flyers either. Very few have reported to have their waitlist clear before T-59.
If they indeed was offering a better U availability to frequent AY flyers up-front that would be one thing, but everyone, from silver to lumo, goes onto waitlist. They are prioritising finding seats for un-frequent flyers who are willing to pay for the upgrades with hard cash.