I think that's a reasonable theory. Trump had rough experiences (i.e. was not obeyed) by Secretaries of Defense during his first term. He needs his personally loyal armed force because of that. Firing a lot of military leadership is also probably part of that.
Actual substantive comment:
My personal theory (looking from this side of the Atlantic) is that ICE got weaponised in this format precisely because the US Military wanted no part of thuggery, eg this 2020 memo: https://www.jcs.mil/Portals/36/Documents/CJCS%20Memo%20to%20...
Is this a reasonable theory?