The GPL mandates that if you modify and distribute GPL licensed software, your derivative work must also be free and open-source. This ensures code cannot be made proprietary.
Other than that, there is no expectation of political stance.
Only in the current ultra-modern age, has politically neutral devolved to meaning that you must agree with me on 99.99%.
The GPL "tolerates" conflicting political opinions, which used to be closer to the norm and thus not political.