Well done, you tried and succeeded in putting your foot very deeply in your mouth, down your throat and out the other end.

Bikes have been ridden with compasses (and vehicle have been using simple compasses without any of the crud/cra* whatever you mentioned) for decades. Don't tell me/others what can't be done, hasn't been done or how it was(n't) done when you weren't around while we were doing it.

No magnetic needle/ball-in-liquid compass I ever used in a car and certainly not on a bicycle EVER needed me to calibrate them. Tanks might be a different story - BUT I used that as a point of illustration and a counter-argument to the statement that one has to walk away from a bike to use a compass, something patently not true if compensation is possible which you yourself argued.

If you want to get into technicalities and magnetic theory and all that cra*, go elsewhere. It's not difficult to find an argument with a physicist. I'm talking reality. If your mileage varies, go a different route but don't try blowing smoke up anyone's butt because you haven't done it yourself and can't believe it works.

While not requiring as much counter-argument as the above, again, you're missing the point. One doesn't HAVE to get off a bike, even a steel one, to use a compass - especially a non-steel one. It's that simple.