The sane way to handle renters vs owners is to restrict the amount rent can increase per year. It might slow gentrification and decrease profit of landowners but it would solve this restaurant's problem.
I own property in The Netherlands and rent it out to tenants. There are increased risks for me because tenants have a lot more rights in The Netherlands than in the USA. But having been a tenant in the past I can appreciate the stability that comes with restricting rental increases.
Does it mean I probably make less money? Yes.
But I like being able to walk around my city and not see homeless people everywhere.