The FIA gave them a favor. Lol. Didn't the FIA change some regulation with the height of the cars from the ground to help Mercedes with their problems with porpoising citing 'safety concerns'? I think changing the rules in the middle of the season could set a bad precedent for the sport. If they start doing it now, they could do it again and again as the season progresses.
I think that's a bit harsh on the FIA, it's not quite accurate, and it may not be the outcome you anticipate.
Wolff was definitely being a bit ridiculous by claiming it's just a safety concern and so needs to be changed, it's true that certain drivers are experiencing discomfort... but it's equally true that this is because of the way they've designed the car. Other designs (e.g. Red Bull) don't have the problem. So Merc should raise their ride height to ensure their drivers are safe, and other teams can do as they like.
However... and it's a big however... the FIA directive is not to raise ride height, but to reduce oscillation of the cars below a certain permitted limit. What this means is that Merc will have to raise their car... and if Red Bull are genuinely unaffected, they can leave their car as is, completely unchanged. The point being that if Red Bull do raise their car, they will be doing so to comply with the regulation, which means they do have the bouncing issue and are just pretending they don't.
So we'll see. Merc may have been pushing for this, but it's not quite the outcome they wanted, it may end up benefitting them, or it may not, I don't think we know yet. Merc could end up looking ridiculous by pushing for a rule that means they have to raise their own car, and no-one else does!
And the FIA certainly aren't doing them a favour... if you recall, the FIA don't like Mercedes, as was evident in the way they ignored their own rules to ensure Verstappen was given the championship last season!