Yes, you are a mean person. Rejecting it does not change reality.

Basically you want to have them move out of the neighborhood in which they lived for years and uproot them over some situation with rats and 'potential' 200 pound 'rat expense'. They will lose their friends, any children will get uprooted and psychologically distressed, everything in their life will change.

In a civilized country, you wouldnt even be able evict them over something trivial as this. Leave aside there being proper regulations to handle everything. But hey - UK has gone out of that classification of 'civilized' since some time ago, hasnt it...