This person does not speak for the entire uncommitted movement. Many people participating will not be voting for Biden come November. And more importantly they won't be participating in any GotV campaigns for the general. There won't be any "heroic" GotV campaigns that carried Biden in 2020. I won't call it for Trump yet. He might not have any juice left in him either. But its going to be close.
If Biden wants my vote he can show he has the strength to twist Bibi's arm. The longer he takes the harder he better twist. His October surprise better be a No Fly Zone over Palestine, '67 borders. Obviously, he won't. But if we can pretend he will I can pretend I'll vote for him. Asking thousands of activists to not just vote for genocide but actively campaign for it is more futile than harassing Biden.
Thing is, independence has been systematically delegitimized as a valid option after years of censorship and state repression of pro-independence Puerto Ricans. Conducting a referendum in the island (especially if it doesn't include diaspora Puerto Ricans) to determine how everyone feels about sovereignty or statehood is a bit like if you asked Americans to vote on how they feel about FALGSC vs. free market capitalism.
That's not to diminish the importance of self determination, obviously at some point it's important that we actually choose what to do, but I just see quite a bit of idealistic posturing from well meaning leftists that don't know mainland Puerto Ricans and how much red scare-like propaganda has been ingrained here against independence. If you bring up independence in conversation with most median age voters, they'll say we'll end up like Cuba or Venezuela, that we'll all starve without our benevolent overlords, etc etc.
Another factor is that the option has just never actually been offered to us in earnest. No politician has ever honestly expected the referendums conducted recently to result in anything but statehood, and the first referendum was obviously expected to result in an overwhelming choice for the free associated state (it was conducted during a period where pro-independence organizers were rounded up and shot). What would even have to change for the issue to be brought up in good faith? The situation would already have to be reaching balkanization (i.e. Cool Zone) levels in the US for an earnest, honest-to-God choice to be offered to Puerto Rico to self determine. Some berniecrat actually wins the presidency and gives us the choice? We'd likely just get rolled back in the next term when mecha-Hitler is elected. It's just a very abstract situation to even picture, and I can't visualize a situation where Puerto Ricans would choose to federate as a state with a crumbling nation. If anything, what's more realistic is the US conducting a forceful annexation through some kind of judicial coup (which they already have set up a body of unelected overseers with the PROMESA act) if there's widespread unrest.