Honestly if your problem is ownership and not the players on the field, just don't go. Showing up and booing is just putting money in Red Bull's pocket and giving shit to the wrong guys.
If Red Bull cared how much money people spent at the stadium, you'd see a more concentrated ad budget and a larger marketing team at the club. They're invested in MLS and American soccer as a whole. That's why single-entity works in MLS. And with SUM, they get a cut of the success (or lack thereof) of the USMNT and USWNT as well. Going to the game or not makes such a minuscule difference to them. Their club in Salzburg regularly fills up 30% of their stadium for league matches. They don't care. You think they're going to care here?