but it only "ran out" on the back straight after Lewis cruised very slowly on the in lap, which was basically not allowed, and ultimately the reason of the 10k fine.
as I said earlier, the FIA and the stewards doesn't do case precedent, unless it's a prescribed penalty written black and white into the regulations. The teams should have and would have known this fact.
no, they should have enough fuel to reach the pits after crossing the line, that's what the "having one litre of fuel for a fuel sample" rule was intended for.
Just that at the moment nothing stops a team from switching off the engine afterwards to make sure they got enough fuel in the tank for the fuel sample.
And no one would know whether the FIA will clarify or amend the regulations to clear things up.
it wasn't ok. McLaren got their punishments for it, albeit a very light one.
There're nothing to stop the stewards handing out much harsher penalty next time the same thing happens. That's the bigger problem, no one could estimate what sort of penalties would be handed down if it ain't written black and white in the regulations.
but at least Lewis was the last car to cross the line and there was no one behind, so it wasn't dangerous in this case.
Lewis most probably did one more lap than originally planned after stuffing the first flyer and then find himself have enough time (just) to start the next flyer. But this is just pure speculation, and perhaps McLaren planned for another flyer but didn't put quite enough fuel. And they got fined and reprimanded for that action.
At the end of the day, with the FIA, there are no case precedent, F1 ain't run under the common law system. (And this is the nicest way I can put it, FIA and the stewards ain't known for consistency in their decisions anyway).