I legitimately cannot think of a single reason or scenario this benefits Newcastle. I was telling a buddy of mine that they should recognize that they aren't a big 6 type of club, or Bayern Munich, PSG, Barcelona, Madrid etc., and it so it doesn't benefit them in any way shape or form, and I don't mean that in a "little brother" type of comment. I mean it in a "this doesn't help you get bigger, take the next step etc." sort of way. If you are Madrid or PSG then sure, you can let that player rot because there's another guys behind him or they can money whip anyone for the big career move. Newcastle can't do that.
They are a step below the top tier, and how do you get there? You are smart, you sell, you make money and you reinvest that money in a myriad of ways. Plus, this KILLS their ability to sign guys not only right now but in the future. Who wants to go to a club that holds them with a gun over the barrel? No one, and that is exactly what they need to be doing right now. Buying next level guys all of the team.