Re: Sorry, I still don't get it...
The issue is that when you stop for tyres, your whole pit stop is somewhere in the 20 - 25 ish seconds (depends on circuit) which is the time spent travelling at the pit lane speed limit and the few seconds that you are stationary.
When Lewis stopped for tyres, Vettel could keep going at full racing speed on the circuit so built up about 20ish seconds of track distance. When Vettel stopped, Lewis was limited to the VSC speed, so could only cover about half the track distance that Vettel could in the same time frame. This effectively gifted about 10 seconds worth of track distance to Vettel, enough to bring him out in front.
The rule needs to be rethought. It was brought in after the Bianchi tragedy to neutralise the race while marshals are on the track. The idea is that nobody gains an advantage, not to gift the driver in 3rd place an easy victory.
I mostly feel for Kimi. He had been in front of Vettel all weekend and ended up behind, although knowing the way Ferrari operate he would probably have been instructed to give up his place anyway if the VSC incident hadn't happened.