I think the stringers approach is unprofessional for 1 who claims to string at tourneys. As Drak has said, get some tubing of your own and use it. It should be standard in any stringers' tool kit.
As for the management issue, I'd consider letting the scenario of the stringer string a rqt with a split grommet, and then the rqt coming back with a premature breakage due to the grommet. Management won't be happy if they have to replace the string job at their expense due a lack of professionalism.
Babolat Strike 18 x 20; Wimbledon stringing team since '04 - Head Wimbledon stringer '14; Babolat stringing team '10-'14. Twitter - @therqtstringer