Look, Kimi absolutely deserved a penalty for not lifting during the yellow flag. It’s not up to him to determine whether it was safe or not. But I think the penalty was unduly harsh. It was the same penalty Seb got for his red mist incident with Lewis. Looking at a description of the penalties:
The drive-through penalty requires the driver to enter the pitlane, drive through it while obeying its speed limit, and exit without stopping. Drive-through penalties are normally imposed for minor offences, for example kerb-hopping at chicanes, ignoring yellow flags, or cutting corners. As a drive-through penalty does not require the driver to stop and pit, it is less costly to a driver's race times than a stop-go penalty.
The ten-second (or "stop-go") penalty requires the driver to enter the pitlane, stop at his pit for ten seconds, and exit again. As the stop is designed to punish the driver for an offence, team mechanics are forbidden to work on the offending car at any time while the driver is serving the penalty. Stop-go penalties are generally imposed for more serious offences, such as jump starts, pit lane speeding, ignoring blue flags, or unfair blocking. The ten second halt makes a stop-go penalty much more costly to a driver's race time than a drive-through penalty.
So a drive-through would have been much more appropriate. But whatever. On to Monza.