Pfff... it's a shifter.

As I implied, the fact that t.del is unfamiliar with Shimano's stupid sticky STI grease says absolutely nothing about his ability to perform general bike maintenance, all of which is child's play relative to understanding STIs.

Your 'concern' that he's endangering his 'customers' (if that's what you can call friends and family paying a token fee) is insulting.

As for the mention of public liability insurance, that just sounds crazy paranoid... but then again, I live in a civilised country with health care; maybe American friends and family will sue if you're such an utter schmuck you can't set up a bike safely.