The fact that many of the names on the list aren’t traditional Democrats ― or self-identified Democrats at all ― makes it all the more valuable.

And yet, since he dropped out of the primary, Sanders has steadfastly refused to hand over his list to the Democratic Party, much to the chagrin of those who say it could be crucial to help build opposition to Donald Trump’s presidency.

Bernie Sanders’ Team Explains Why He Won’t Hand Over His Donor List | HuffPost

Also, the tone his team uses is one reason people don’t like them.