EDIT: Observe the user below spamming multiple replies to the same comment. This is part of the gaslighting gish-gallop tactic I've noted. There is a user here I suspect of having many alt accounts and who frequently does this. I encourage you to report them for spam.

what methodology is available to you to prove such an accusation?

If I may, a thing called logic.

• If your goal is to minimize genocide, both in Palestine and Ukraine.
• If your goal is to ensure that we don't fall further into fascism.
• If the choices on the ballot in November are a constant, regardless of anything else that happens.
• If you understand the nature of entropy in that maintaining let alone building-upon a trillion-piece puzzle is exceedingly more taxing than smashing it.
• If other guy is significantly-worse for Ukrainians, Palestinians, US, and the World.
• If you understand the mathematical trend of FPTP and the Spoiler Effect.

.... Then one understands the logical choice is voting for Biden and doing anything else from not voting, voting Republican, voting 3rd-party, writing-in -- is utterly self-defeating and short-sighted to the aforementioned goals.

If you don't understand these things, then yes, one might have built their ardent beliefs atop a house of cards.