There seems to be a bug with the Curve.IsPlanar(tolerance).
The sample Brep is planar with a tolerance of 1 mm (knowing the deviation is 0.89) by the test in Surface.IsPlanar(tolerance). However, the results are different in Curve.IsPlanar(tolerance) and Brep.CreatePlanarBreps(curve, tolerance). I have to increase the tolerance until 4 to make it pass the IsPlanar for the curve.
Is this a bug? if not, what is the reason/logic why the different results from IsPlanar check for the curve and surface?