Stretching my imagination I come up with a couple more possibilities ....
Was SP looking to buy a dog , or guard dog for his business .... were CM & SC planning to move anyway , or were they told to get rid of the pet (barking when no one around) ... I have owned pets when living in apartments and it is a real pain taking them up and down elevators 2 to 3 times a day , never mind cleaning up the crap afterward and how dogs scare some other tenants
Was CM wanting to get a job with SP's company ... doubt it , sounds like CM did not care to work , besides it sounds like SP had a good and dependable crew.
Was SP there to buy something legitimate , tools , equipment etc ?
All in all , there is a good possibility they had earlier conversations at coffee shops and knew each other from there , SB was known to interact with customers ..... so SP may not have felt he was with total strangers when he went to their home.