Tactical error no question. It wasn't a bad decision it was a WRONG decision. Firstly it's protocol that the lead driver gets first shot of the fresh tyres. Second there was no undercut threat, the race was being managed perfectly. Until then. In the short term it probably won't damage harmony too much but the seeds of distrust are being sowed too often.
The rearranging of your drivers to facilitate winning the WDC doesn't normally occur (unless you were Schumacher) unless there is a tight situation in the points and winning is quite feasible. 76 point leads don't tend to evaporate, and Max isn't your normal driver, some say as good as Senna. The reason we are even in the zone of thinking about the WCC apart from having a fast reliable car, is we have two good drivers, Red Bull only have one. 51 points is well on and we need both drivers scoring heavily. Max will not stop winning.