It wasn't like he has never ridden on a normal bike set up, and it wasn't like he was handed a tesco generic bike with forks wrong way around. He had to ride about 6 miles on a bike that was slightly different to his usual one. Every little may help, but he was hardly on a Clown bike. If he had then Millers praise would have been worthy.
These are very short-sighted and uninformed comments/observations and it appears you don't really understand how crucial a pro rider's precise positioning, bike set-up and personal preferences are to getting the most out of himself. Teams like Sky spend immense time and effort in investigating and establishing these things. This wasn't a bunch of teenagers racing each other around the supermarket car park. Froome was needing to stay with the strongest Tour GC riders in the world on the final (pretty tough) climb of a crucial Alpine stage, having crashed, whacked his knee and skinned and bruised his arms/legs/shoulder/back, had to chase back on, and with all of his rivals doing their best to drop him, so saying he was 'hardly on a clown's bike' is irrelevant and spectacularly missing the point.
Racing cyclists at this level are so intensely fine-tuned that anything detracting from their exact positional requirements can have a significantly detrimental effect on both the physical ability to get that full-on high-end performance out of oneself and the mental capacity to ignore the fact you're on a bike that feels all wrong (mental strength being pretty important when you're operating at such intense performance levels).
And it doesn't take much for a bike to feel all wrong, even for amateur racers. I used to ride with someone with the same critical body dimensions as me - height, reach, leg length, foot size etc - and (ostensibly) the same application of the Bernard Hinault formula, but when we rode each other's (similarly constructed aluminium-framed) bikes we both felt all wrong and would have had enormous difficulty trying to keep up with fellow racers of similar capability going flat out trying to drop us on an Alpine (or any long) climb while we were feeling so wrong on the wrong bike. The difference in feeling was huge and the constant gnawing need/desire to get back onto your own bike is extremely distracting. I imagine having on top of that to do it with a chainring change that takes days to get used to would have made it even harder.
So yes, Froome's performance in doing what he did on the wrong bike, and in pain after crashing (those types of falls still bloody hurt), is extremely impressive and fully deserving of strong praise.