Obviously not. We can't talk in absolutes here - that's not how it works. The Jays should field all offers for Bo. If someone is willing to pay 80 or 90 cents on the dollar for the player Bo's been for the past 4 seasons, then they should move him, as his value likely decreases as he approaches free agency. But if teams are only paying you 50 cents on the dollar, it's obviously worth the risk that he rebounds next year and will be worth more - even if he's a rental. That obviously comes with risk that he doesn't turn it around and his value bleeds - but that's worth the risk if you can only get 50 cents on the dollar right now.
Just because things went south with JD's health doesn't mean that philosophy was wrong. I just means they ended up with a worst case scenario. Don't react to unique results, stick with the process.