Leeds are supposedly one of the two clubs pushing hardest to sign Bate. So, I'd assume Bielsa/Leeds have plans for him.
Think the reason Bate (and the other two) wants to leave is because we still have Kante, Kovacic and Jorginho while Gilmour is out on loan AND we are supposedly looking to sign a midfielder. It's understandable if the likes of Bate doesn't see a pathway to play regularly in the first team in the near future and wants to leave. As Pizy mentioned in the other thread, when these young players see others are making a name for themselves elsewhere, it's probably hard for them to just sit around, bide their time and hope something will fall their way. Can't blame them if they want take control of their future, especially when we look to be heading back to pre-2019.
Also, the problem with them signing an extension, even a year or two, is that they will give almost all the control of their future to the club. With a year left now, they have practically forced the club to sell them now or get nothing.