There's a long debate to be had about immigration in general. I'd contend, though, that it's in the public interest to look past things like immigration status in certain situations. For example, suppose we're vaccinating against an epidemic. In that case, you definitely don't want anyone to be afraid to come out and get their shot for any reason.
SF doesn't keep illegal immigrants safe from deportation. It says "in these circumstances, we think it's more important that you cooperate with the city than it is for us to try to deport you, so we're going to call a temporary truce".
SF doesn't keep illegal immigrants safe from deportation. It says "in these circumstances, we think it's more important that you cooperate with the city than it is for us to try to deport you, so we're going to call a temporary truce".