Are you saying it's not ok to drive 90km/h in a zone where 120km/h is allowed?

80km/h is the usual maximum allowed speed for trucks, at least in Germany, so no idea how a car driving 90km/h is such a big problem. That's not a "stationary object" at all, far from it. You are even allowed to drive vehicles with a minimum speed of 60km/h on the Autobahn.

If a car driving 90km/h is the cause for a traffic jam there are definitely other factors at play. Not just in zones with a limit of 120km/h but everywhere even without limits.