my guess is because the strategy is to get more people to vote, so they can actually beat republicans in 2020.not calling for the abolishing of ice isn't the same as voicing support for them. you can be against their concentration camps while seeing the need for immigration enforcement.
and the brown people who vote ain't supporting them like they should anyway so why alienate voters in hopes of courting people who will abandon you in short order.
a large number of latinos aren't activated. this is a strategy to do it. i think activating non-voters is a better strategy then trying to win over center leaning right wingers, we've seen they'll vote for trump. even if they aren't down with trump 100%.
it's a numbers game. black people ain't gonna abandon the democratic party over this and the white people who want walls are already supporting MAGA.