Seizing sucks, but I don't think the Maeda engineers factored that into the pulley bolt design.

And yes, some Suntour pulley bolts of that era have remarkably "low profile" hex heads. But I've had worse problems with stuck pulley bolts that need a 3mm Allen to remove - those are all too easy to round out applying break-loose torque, and are then much harder to deal with once the intended tool no longer turns them.

Long ago on my 8-9-10 Y wrench I ground down the socket faces to improve engagement on bolts of this type, so that could help.