But you're wrong. The memo says they can use an administrative warrant - which is to say, a warrant signed by an immigration official, part of the executive branch - to enter a house and arrest someone. The executive branch is authorizing an executive branch official to enter a home, bypassing the judicial branch.

The CRUCIAL thing to note is that ICE gets stuff wrong. Their info is often stale or flat wrong - so even though they say "this is only for illegal immigrants, don't worry about it ;)", it can ABSOLUTELY affect citizens.

Note also that, since it's ICE and immigration officials (again: all executive branch) making these determinations, the executive is also deciding whether there's probable cause to think that an illegal immigrant is in a particular house. This damage to due process is ostensibly only aimed at immigrants, but it affects all of us.

Despite the word "warrant" being present, an “administrative warrant” does not allow law enforcement to enter private property.

If they find a illegal immigrant on public streets, they can be detained, but still cannot enter a private residence (even if occupied by an illegal immigrant) as it would violate the 4th amendment.