Let's put this into perspective. Pep, Klopp, Arteta etc would have told their players to think of the bigger picture and not push it too much. In the case of Gabriel and Saka they were assessed by their national teams as having slight knocks and decided not to risk it. From City's side by all accounts the Portuguese lads agreed with the national coach that they'd play the 1st game and then leave the camp. Other Arsenal players decided they wanted to play full matches - Rice, Kivior and Odegaard. Zinchenko played the full match for Ukraine but that was a play off for the Euros so fair enough.
In my opinion what was stupid was Walker getting a twinge, coming off AND THEN COMING BACK ON! He'll get read the riot act by City. Totally irresponsible.
Rice won't play vs Belgium as I'm sure there's an agreement in place with Arsenal on that - I'd be surprised if Stones or Foden did either.