I don’t see the real problem OP.
You encountered some dicks who happen to cycle and feel that you must be able to either righteously defend all cyclists collective honour it else whole heartedly agree with your Ranty, motorway man, colleague who can’t differentiate between “bloody cyclists” and regular human beings.
Every time one of my colleagues recounts yet another non-incident involving their metal box and a cyclist (hoping for some sort of rise out of me) I tend to just retort with, something along the lines of:
“Yeah there seem to be a lot of **** on the roads these days, some in cars, some in vans or busses, and some on push bikes. Its almost like a proportion of the population are morons, no matter what form of transport they use…
Just give some qualified agreement to your colleague, the cyclists you encountered were morons, its inevitable that some people always will be, not all cyclists are, and road ragey twattery, beeping for the sake of registering your opinion or going that step further and making deliberate contact (I’ve had it happen) can’t ever really be justified.