I wouldn't worry about the indicators - as long as they flash and are not on constantly it shouldn't be a problem.
(Unless in his opinion they mislead other motorists)
The minimum tread depth is 1mm across the whole tread pattern so you should be alright if it's only reached the wear indicator - but, remember tyres are the only point of contact with the road and as such they are THE most important part on any bike.
- By the way these are not stupid questions ; ask away, as someone on here will always be able to help!
