I agree that Lufthansa has to accept the repercussions of their policy, and if somebody asks me for a favor and says they need to because "it's their policy", I'd squint pretty hard at them, that's not really the jurisdiction of policy.

For all the people who believe that the policy is the safest and safety comes first, that's a fine opinion, but if other people don't agree to that tradeoff (absolute safety versus demands on a crowded airport timeslot) you have to accept that, you can't impose your opinion about safety on everybody else's schedule.

I can also see that the air traffic controller might have messed up. Perhaps they intended to squeeze Lufthansa in when they told them to wait, and maybe they forgot and didn't, and then when pressed they got irritated, that's how overworked people typically would react; but still it was their call.

Perhaps this flight is never late so they never encountered this situation before. We can't expect everything to go smoothly all the time, so we don't necessarily need policy changes because of what happened, simply adjust what expectations we should have. And if Lufthansa expects future conflicts, now is the time to work it out with the appropriate parties (i.e. not the whole internet)