Arn,
It's not so much that the firewall is weak, it is simply that this is where Cessna attached the nosegear strut. Apply sufficient force to that strut, via the nose tire, and you can bend or buckle the firewall.
By the way, right behind that firewall and attached to it, is a tunnel, which contains the cables for the elevators and ailerons. If you bend the firewall, it can impinge on that tunnel, and conflict with the control circuit movements. I have found this to be the case in two Cessna tri gear airplanes, one a 172 and one a 182.
A MANDATORY pre flight check on these airplanes, whether they are used off or on airports, is to run the controls throughout the EXTREME limits of their movements and look for any anomalies. Just moving the yoke fore and aft, followed by moving it right to left won't find this sort of problem (unless it's REALLY bad).
You need to run the yoke all the way to the forward and far left limit, holding full left aileron, move the yoke smoothly to the aft limit (in here is where you'll find a bent firewall) then transition the ailerons to the far right limit, then move the yoke full forward to its limit, and then move the aileron to its full left limit, ie: the starting point. THAT is checking the conbtrol circuit for freedom, not just stirring the yoke, as I see most people do.
Firewall problems due to nosegear strikes aren't common, but they happen. It doesn't mean it's a bad airplane, simply that you need to take VERY good care of that nosegear attach point.
Note that on the Cessna 206, Cessna moved the nosegear attach point to the engine mount for this very reason. Bend that, and it's a lot cheaper and easier to replace. There may have been other reasons to move it, but that's a big one in operational use, at least.
The man from Peterson is absolutely correct that holding the nose gear off with the canard will help to prevent this. Understand however, that its hard to see around that big nose, and easy to hit something you don't see. For established airstrips, the airplane should be fine. For real off airport, I'd be very careful.
I have a couple friends who used their 182's on skis. Both wound up with bent firewalls. Skis are tough on gear.
MTV