I've know Tim for nearly 20 years. And his brother Tom. They are strange dudes. But never unfriendly, at least to me.
I run the Ann Arbor pinball museum. We have 200 games, which is close to what Tim handles. So i have a pretty good handle on broken stuff. The difference is Tim is in Las Vegas, and open to the public every day for 12 hours. Like every day, even Christmas. I can't even fathom the work involved in doing that gig. Sometimes i'd be grumpy too.
Actually people do say i'm grumpy. But then they just make fun of me. Seems to work well for everyone. Self deprecating behavior is the way to go at our place. I get asked a lot of questions about people fixing their games. Heck sometimes they show up with broken boards. It gets a bit frustrating sometimes. I try and help but it's difficult to do sometimes if you don't know the individual and what they are capable of doing (or not doing.)
Also it should be understood that Tim has invested 50 years of his life learning to fix machines. When you have that much time in the gig, and a newbie comes up with a question (that probably could have been answered with a google search), it could be frustrating. Now imagine that happening 10 times a day, every day.
Now imagine mom dropping off her kids at the PHoF and going shopping. There's no entrance fee, so it's low cost baby sitting. No parents so kids run wild. This happens every day, and again, I have to guess that this is really frustrating for Tim. So yes Tim does yell at kids now and then.
Now imagine the bathroom. Did you know that about once a month, someone "paints" the walls of Tim's bathroom with crap? I'm not kidding about this. Someone actually takes a dump, and then hand paints (ass paints?) the walls with it. Can you imagine cleaning that? Can you imagine the frustration involved with that? If it was me, I would view everyone as a potential "wall painter" and wonder to myself, "did this guy/girl just paint my bathroom walls with poop?" Hmmm..... Tim wants to install a camera, but knows he legally can't. He wants to catch this person(s), but it's been a cat and mouse game for years and Tim is frustrated by it.
Again imagine a guy, slightly impaired, coming in and playing Xenon. Then that same person wins a bunch of credits and demands from Tim he "get paid." An argument ensues and Tim throws the guy out. This is the PHoF, not some casino gaming room. Then the guy sues Tim over this. Costs Tim $20,000 in legal fee.
Being in Las Vegas, my guess is it's not the games the drive Tim nuts, it's the people. That's just a guess though. So for the average guy to walk in and call Tim "unfriendly", well, you need to walk a mile in his shoes before you start flapping your jaw. Because no one has any idea what Tim goes through to keep the PHoF open.