It is a one year deal. If KC was offering slightly more money and also only a one year deal, consider the aggravation of selling your house, finding a new place to live, jusbt to do it again a year later. he probably has friends in Pittsburgh both on and off the team. I can think of a lot of reasons not to switch teams/cities particularly for a one year deal. For a 6 year this is my new home kinda deal -different story.
You cite some very logical and practical reasons on why a player would decide to remain with his existing team. However, NFL diva's like JuJu (who start tweeting about being on another team before they have even left) often don't use logical, practical reasons. lol