Is this mechanic retarded?

Came in to shop I usually go to, but my mechanic is off today they had another dude there.

I asked him to check alternator/waterpump/fuelpump.

He checked my current, then told me:

How can I check your to check fuelpump/waterpump?’ If it works it works even if I check it now; it can stop working when you turn the corner.

Is he right or retarded?