If the lower end of the fork will spin, & not hurt anything, why not spin it so the tab is on the outside & cut & file it, then spin it back around? I would sure rather bleed brakes than disassemble forks & triple trees.
After that if you deviate from the instructions and disconnect one end or the other of the hydraulic hose between the disc unit and the master cylinder you can then route the hose without disassembling the rest of the front end. the only downside to this is that you will then have to bleed the brakes, a simple and quick job.