In your opinion, was Eisenhower the best man for SHAEF?
I believe Ike was under-appreciated as SHAEF commander and as President of the United States. But this incident shows an unseemly side to him. Devers had been a rival, also under consideration for the SHAEF command. Altough Ike told Marshall he had no objection to Devers getting command of 6th AG, this incident shows that there was some lingering resentment.
I guess that the best that can be said is that Ike was human, and not perfect.
On the other hand, Patton is at the edge of the Saar, smaller than the Ruhr, but still an important industrial district. Bradley also needs Patton to take the Saar to protect his flank as 1st and 9th Armies attack the Ruhr, the taking of which would end Germany's ability to wage war in the long term.
Ike and Marshall held firm to go with Devers' invasion of the South of France when Churchill pulled out all the stops to try to persuade Roosevelt to keep those troops in Italy to pursue his dream of running forces up the Ljubljana Gap into Austria and Hungary.
So, I don't think it was entirely personalities, but it's pretty clear these guys rubbed each other the wrong way.