Things cyclists should know … POV driver who's incapable of cycling

This is exactly the point. If the cyclist in the pic is in the right hand half of the lane, the cyclist cannot be over taken safely. If the cyclist is in the left hand half of the lane, the cyclist can over taken safely.

If a cyclist is in the right hand side of the lane, for no discernable reason for an extended period of time, the cyclist is effectively blocking opportunities for vehicles to safely overtake.

Actually my point was merely that the photo and guidance makes no sense once you move beyond face value, it had nothing to do with why a cyclist might be on the right hand side of the road or whether they even need a reason to do so.

My personal opinion as a cyclist and a car driver who lives in the country is that cyclists can take whatever position they feel appropriate in a lane and don't need a reason. As for overtaking a rider who has taken a position in the right hand of the lane, then so long as it's clear that the cyclist is not about to enter the other lane themselves, then simply by being in the other lane and not overtaking faster than necessary you are deemed to be safe.

Now if we want to talk about road users who are hard to overtake safely then we should be talking about horse riders...