No. That is a net negative. But a cyclist in an unsafe position should be given a path to safety regardless of what happens to other traffic. A cyclist that is not on a roundabout yet is perfectly safe, and stopping traffic on a roundabout to yield to traffic that does not have right of way is not ok.

Ah, OK – that makes sense. In my country, it's not a question of being nice but a part of the road rules. Loosely translated excerpt:

> The driver has the following responsibilities: (...) to do his utmost to ensure that other road users are not endangered, especially the most vulnerable (pedestrians, cyclists and electric scooter riders)

If a cyclist ignored the law and entered a roundabout anyway then I would definitely stop. But if they're waiting in front of a yield sign then obviously not.