GrasB, you take yourself far too seriously - we know how good, knowledgeable and dedicated you are - you tell us in nearly every post - relax a bit man
Your people skills also need development by the sounds of things - I have had people join me out on the road whilst doing intervals (power / HR zones, etc), and a friendly word to let them know what I am doing has always sufficed and not ruined my training ride.
For example, a couple of weeks ago I saw a cyclist at some lights and he asked if he could ride with me - I simply told him I was doing 1 hour at a certain HR and so my speed may shoot up and down a bit to keep in range, but he got on my wheel which wasn't a problem - I got my desired training ride, I met a new cycling buddy and he did his first 20 miles in 1 hour by trying to stick to my wheel - everyone was a winner