Having time to think about I think I get where these is coming from now. But I will say 2 things here
First, Biden, or any other Democrat, if they were somehow on board with defunding the police (and by defunding I mean slashing their budgets and redirecting into social goods and services) it'll be their job as politicians to try to sell this concept to the American electorate not on activists. So let's say I concede for the sake of argument that phrasing of "defund the police" is electorally toxic now and will be at least until November. Well then I guess they can try to communicate this message in a way that isn't? Like, there's some options here.
Someone like Biden can probably argue "we're making the job harder on cops by giving them too many responsibilities. Cops are our mental health workers, social workers, guidance counselors in schools, drug abuse consolers, animal control and more. We need to refocus the job of the police on fighting crime and solving cases and invest social workers and other experts to handle these social ills". Something like that. if that's too "radical" then he fallback to the language of reform but it will be on those of us who are activists to actually push him further.
This brings me to my second point and that that Biden didn't even say he wanted reforms. He said the police are willing to reform themselves let's give them more money to do it. What this communicates to me is he's not interested in reforms at all. There's much needed reforms at the federal level he and the house Dems can pursue like ending drug criminalization, ending criminalization of sex work, he can vow to end operation relentless pursuit and a whole host of others I'm forgetting. Instead of committing to any of that he tells us the cops can reform themselves let's give them even more money. This reads as someone who isn't interested in changing anything at all despite the protests despite the outcry despite the massive support this movement is gaining.
So yeah I still remain disappointed (but not surprised) with all that said even while conceding for the sake of argument that defund the police is an electorally alienating slogan for a politician like Biden to adopt. It's not that he hasn't adopt that position it's just he isn't offering the movement anything