went t0 the hardware store and purchased a 6mm plastic knob ($4.60 US). here it is next to the stock bolt:
clamped the new knob in my bicycle repair vice to cut it:
here it is cut down:
and installed:
no more torx required for removal!

clamped the new knob in my bicycle repair vice to cut it:

here it is cut down:

and installed:

no more torx required for removal!