I do not understand the eagerness here. Extra weight well behind the axles is always a problem. Of course it will not effect a 2,7 ton 4x4 like it would affect a Ford Mondeo.You are seriously comparing adding a 1000lb plow built to drag on the ground while hanging 4 feet in front of the axle and pushing 500lbs of snow into a pile to adding a 50lb winch that will be used while the vehicle is not in motion? I will stand by my previous comment that while it "may" make a difference that 50lbs isn't going to be noticeable. In my previous example of adding the bikes to the rear of the vehicle you would need to a lighter sprung front end. When you add an oversize spare and 10gallons of fuel to the back end of the truck are you planning on changing your front springs again? Throw 4 bikes on the back hanging 6ft behind the rear axle, how much will that affect your handling. Even if you add another 100 lbs of mass to the front you are talking about 1.5% of the total system. The good ole days of adding 275 lbs of winch and bumper while removing a 10lb bumper don't apply here. I am going to trust Ineos here and simply not worry or demand anything. Go ahead and demand a front spring though that has 1.5% more load carrying capacity, maybe instead of a 600lb spring rate it is 609 lb.
And it’s regularly not about the big problem if you have the load at one and from time to time (bikes).
It matters for sure when you add weight that will not be removed. And it matters specifically at the front axle as this has a spring rate which is adapted to the expected weight (motor, driver weight between the axles).
As someone pointed out before the weight in front of the axles is pushing with factor x on the nearest axle while it leightens the axle on the other side. So the weight, especially in dynamic environments, is much higher . This can and probably will affect the front springs after a while.
Comparing this to the rear axle is not targeting the aim.
The springs of the rear axle are made to cope with the majority of the payload and the towing forces.
Nevertheless vehicles which drive regularly with a heavy trailer or fully loaded will probably need a new spring setup more early than the empty fun driver.
As it’s just about the laws of leverage there is not to much place for discussion from my point of view.