I think it's just generally, you don't want someone frail doing a job with you; they'll likely pass out after a single flesh wound, or get an infection and die after their first run. Just, not a thing anyone looks for in a partner. Arguably this should also be if you have someone with a 1 in Body, as they're also pretty vulnerable. Remind me to consider a houserule of "1 point of Notoriety for every non-special attribute at 1"...