In Australia, Alonso did hit the throttle again, but not enough to actually accelerate again. The speed trace shows the car decelerating all the way until Alonso accelerated hard again exiting the turn - minus a very small portion in the middle where the speed flattened for just a moment when he blipped the throttle momentarily. That merely reduced the rate of deceleration for a moment. It didn't actually accelerate the car. He wasn't speeding up and slowing down. He slowed, maintained a constant speed very briefly, then slowed again before accelerating out of the turn.
Anyway, of course none of these instances is exactly the same, but they are all examples of erratic, 'potentially dangerous' driving (which could easily describe many things we see every session of every race weekend). Some of them were very unsporting, and some actually ended in contact between the offending driver and another. Another I forgot about was Lewis lifting in the middle of Raidillon with Vettel right on his gearbox, and the other one where Vettel drove into him, he said it was in retaliation for Lewis brake-checking him earlier. There are so many. They happen all the time. For most of these incidents, it's not really strange that they don't get investigated. What's strange is that out of all of them, this one is the only one that suddenly ticked the boxes in just such a way as to be penalized harshly - even though the stewards said themselves that he didn't cause the crash. Pretty much all of the others went without so much as an investigation, and the biggest penalty was half of what Alonso got in Oz.
Palmer said George bears at minimum a portion of the responsibility for his crash, and (when he pointed out Alonso's flashing light at the same time George was apparently changing a setting) hinted that Russell didn't realize that Alonso had scrubbed off speed, and attempted to take the corner too hot. That was his first mistake. His second mistake was trying to change direction too quickly once he was in the gravel trap. Palmer also said that Russel turned in more severely than any other lap as per his steering trace.