You deiced already- lots of people that know this person, and who have visited this person and some who have seen him once have all replied to you...
There are a lot of things that can be going on with a person that makes then seem or be unapproachable or gruff- some in the 'wiring' some in the environment and sometimes both-
I'd think it would be cool if there was a 'ticket' system or something developed for "next to nothing" (in terms of overhead) that would flag problem machines down and let a person prioritize- but I haven't figured it out yet.