If the seller is offended then that's their fault for getting emotional in a business transaction.

I am emotionally involved in my current house because of my neighbors.

Then they do a quick conversion to condos in two years and raises the property value.Such buyers are most likely buying on emotions because they are purely looking for a nice home to live (not cash flow), possibly buying in that location because of proximity to family or about to start a family, etc; so they will pay top dollar.  

Then join a local REI group and begin using this formula to overcome your fear of the unknown....Definite Goal/Plans + Faith + Emotion + Action  = All Human AccomplishmentFaith = Knowing you can accomplish your goal / Self ConfidenceEmotion = Feeling you can accomplish your goal / objectiveIf you feel that you are deficient in any element, focus on working on that until you feel you're ready to take action.I wish you the best.

Brandt is correct, there is no place in business for emotions, leave your heart at home where it belongs.

At the end of the day make the offer with your numbers, not emotion, and if it gets accepted right on.

Most owners or owners acting as PMs keep it professional with no emotional ties to tenants and keep it running as a business.

Personally, I would walk away, but he's emotionally invested, so, I'm trying to give him at least some tips, where he should ask for changes in the contract, which probably won't happen. 

Remember to leave emotion out of it and think "Future Rental".

Let the seller know this is not an emotional buy and #'s must work.