Whether Democrats were conservative or not back then is not the issue but the deployment of the national guards by a former president, who saw the need to use such authority in extenuating circumstances. When the protesters invaded an ICE facility they became rioters. When they continued looting, burning vehicles, throwing rocks at officers, breaking curfew and defeying police orders, destroying government property etc, criminal crimes, extenuating circumstances called for the National guards to be deployed to protect federal property and personnel and to help the LA law enforcement enforce the law. The US President, Democrat or Republican have the discretion to override a governor denial of enforcement.

The law is pretty clear on when the President can send the military into states to perform police action like that. If the ICE agents couldn't do their jobs because of the protesters, then maybe Trump could activate the Guard for that, but there was no time when ICE stopped arresting people. And those "agents" are driving around in unmarked vehicles, and "doing their job" with the faces covered and wearing no identification. Just generic military gear like ballistic vests and helmets. Not even a badge.