Oligarchs. You’re missing oligarchs. The issue with Ukrainian agricultire is that a lot of it is a big, concentrated business with ties to Western capital on top of the traditional post-soviet oligarchy. This influences actions of both Ukrainian and EU politicians. The matters of imports or transit from Ukraine could be very well sorted out for the short term, but no one in power is really willing to do so.
In the long term Polish agriculture faces a serious challenge from Ukraine when it gets more and more integrated with the west but it’s also not so binary in terms of who floods whom with produce.