Grand jury refuse to indict 6 Democrats for video message

Just watched JVL and Andrew Egger discuss this case where the DOJ tried to criminally indict six lawmakers for reminding service members to obey the Constitution, and a grand jury refused to go along. They praised the legal system of judges, juries and grand juries for holding the line, but I didn't think JVL went dark enough with what might happen in the next 3 years if Trump gets sick of that system.

I see two possibilities, though others with imagination might see more:

1. Can the administration possibly meddle with the "random algorithms" that select the jury pool? That looks like a possible juicy contract for Palantir or someone similar to meddle with that. 2. It is already standard procedure in Minnesota for ICE to arrest and detain no-name brown people and protesters without charge, and to refuse court orders (mostly through malicious incompetence) or their release. How long until Trump gets fed up failing in front of juries and grand juries and extends this practice to high profile political enemies? What is actually stopping masked ICE agents from surrounding Mark Kelly on his way out of the building and just locking him up indefinitely if they can't get a grand jury to play ball?