Obamacare had mandates paired with subsidies for poorer people who couldn't afford it.
Republicans railed against mandates as deathknell to freedom, even though they re required for insurance markets to work properly and not have free riders.
Now they insist on mandates for illegals -most of whom would be poor enough to get subsidies- without paring them with subsidies.
So, freedom for me, but not for thee.
The calculus is that by adding an additional financial burden they can make the number of immigrants qualifying smaller.