It conjures up images of a criminal fleeing from law enforcement, and rushing into a church where they are protected from arrest. It should be called 'Local Police do THEIR Job, Federal ICE Agents do THEIR job'.
And the policy of allowing "... Boston police to collaborate with U.S. Immigration and Customs Enforcement "on issues of significant public safety, such as human trafficking, child exploitation, drug and weapons trafficking, and cybercrimes, while refraining from involvement in civil immigration enforcement" sounds perfectly reasonable.
Hopefully, this will come before a reasonable judge.

is that for many decades, municipal, county, and state investigative units (including LEO) have had "partnerships" and "MOUs" (Memorandums of Understanding) with the equivalent federal authorities to carry out a variety of work, including law enforcement.

Since each entity was usually underfunded by their respective funding authorities, partnering would allow them to "pool resources" for a common goal.

However when you have a particular entity - in this case, a loon federal administration, coming in and "weaponizing" their power by unilaterally operating in a locale, with little or no communication and/or coordination with the municipal/county/state organizations, then you have a break in the agreements and trust, and that is what has happened here.

But most state and local governments do not have laws governing Immigration -- so there IS no 'equivalent authority'. That authority lies solely with the federal government.
And, in the case of Boston, the local law enforcement WILL assist the Immigration agents in the cases where their duties DO overlap.

(I appreciate your comment -- it makes me work my lazy brain a little harder!)