Wrong, wrong, wrong. It is 100% the fault of the person making an unsafe lane change if there is an accident, NOT the person who was driving too slow for your taste. You still have not given a single legitimate reason why low speed limits (by themselves), or slow drivers (by themselves) are dangerous.
People who are driving at a speed that is far outside the average speed on a particular road are a danger simply because the difference between their speed and others is likely to be large. Note that whether they're going "faster" or "slower" doesn't matter - it's the difference in speed.
If I'm going 90MPH and I bump someone going 89MPH we'll be fine and have minimal damage to our cars. If I'm going 45 and bump someone going 44 it's the same. But bumping someone who's going 45 when you're going 90 will result in a major accident.
I remember reading something a few years ago said by a patrol officer. Basically, fast drivers and slow drivers cause the same number of accidents. But in his experience the fast drivers were part of the accident while the slow drivers caused other people to have an accident (trying to avoid the slow poke) and drove off possibly unaware that they had caused an accident.