If your pensioner would be in with that, you could start to change the following behavior, so that the dog learns constant controlling isn’t worth it anymore. That would mean there is no need to defend its position as “master controller” anymore and could allow for a better relationship between you and the dog.

How?

Thanks for saying it’s a territorial dog, knowing this is already half the road to success.

Don’t put the burden on people. Cities worldwide are hostile to cyclists and even pedestrians.