It's baffling! As you say, it was all over the official footage Sony presented, which set an expectation it'll be there on release day. Sony have done a dreadful job at promoting / showcasing the PS5 Pro, this GT7 update delay, whilst likely not Sony's fault directly, just kinda adds to the feeling of lack of focus, communication and planning on Sony's behalf. It's all very strange for a company that's definitely no stranger to all of this.
Not too fussed about it not being ready though for Thursday. There's going to be so much else to play and try, it's almost an overwhelming number of titles, boost mode will also have me revisiting titles which aren't enhanced.