Apple can ask Google to do business, but Google will be under court order to respond, "Sorry, we can't."
In that situation, Apple would not have any obligations to the court. Google would be responsible for avoiding doing business with Apple.
Obviously, this would impact Apple's economic interests, so they want a seat at the table.
You can't really end run around this by doing it in the other direction, because it has the same effect - even though they could not hold apple in contempt, they could hold google, which has the same effect.
Again, it's gotten looser more recently, but forever, this was not okay, and the underlying precedent has not actually changed. Everyone does expect SCOTUS to make a statement case in the next few years about this.
In any case - Imagine i ordered you not to have contact with your best friend, without them desiring this. An argument that i've only enjoined you falls flat - at best, i've had serious affect on their constitutional right to free association, etc.
Saying "yeah but only you will get held in contempt" doesn't really work.
This is even part of the FRCP - see 65(d)(2)
The only exception is basically aiding and abetting.
This is well settled caselaw basically forever. I posted it elsewhere in the thread, but here's a very recent example: https://reason.com/volokh/2025/01/24/google-as-non-party-not...
(Youtube can't be ordered by a federal court to take down posts as part of an injunction, when they aren't party to the case).
The court may want to keep whatever scheduling it has, but it's going to royally screw itself if it tries to order an injunction that affects the rights of non-parties in a meaningful way like this, without being really really careful about it.
Especially with SCOTUS just itching to find important cases where they can reinforce the limited nature of injunctions and ensure courts only grant relief that deals with the parties at hand.