when i got lucifer neutered someone at work told me i was cruel to do that!! she said that "cats should be allowed to have fun, youre taking all the fun out of life for him". she was 100 % serious. in her defence shes spanish and has a different attitude to animals. she got a reeled off lecture about illness, roaming,spraying,stress etc
when i told my mum that i was hoping to keep lucifer either inside or with a cat-proofed garden she told me she thought it was cruel, since then shes had "an education"
and came to visit last weekend and agreed that he doesnt seem to miss the outside world and is happier in himself than our old indoor/outside cat was despite our best efforts. my mums a cat lover but just still has fairly out dated opinions and with some patient explanations shes seen the light, maybe its possible to do the same with your neigbour? as jackspratt suggested a quick cuppa might cure all? mind you that depends if you care about her opinion!