It doesn't force anyone to agree with any changes. It says "the recipient can use this under GPL v2 or any later version as published by the FSF", which means

It doesn't force anyone to agree with any changes. It says "the recipient can use this under GPL v2 or any later version as published by the FSF", which means if they recipient is happy with the rights they got under GPL v2 they can keep using it under that version for as long as they like. The only person agreeing to future license changes is the publisher of the code, and they're the ones that chose to publish it under "GPLv2+" or whatever.