I think most inexperienced officials are unapproachable for two reasons: they lack confidence and they don't know what to say. Both things come with time. Obviously, the more you work, the more you interact with coaches, the more comfortable you'll feel. But before that happens, many officials feel threatened and respond the only way they know how: with a technical foul.
As you become more epxerienced and move up, you have to become more approachable. Varsity coaches expect to be able to ask questions. Some know how to ask them, others don't. I'm less approachable with those who don't. But if you're going to be approachable, you have to be prepared to answer their questions.
Who he ask you about a call, tell him what you saw. If he has a different opinion, tell him you didn't see it that way or you'll take a look at it next time. If you missed it, tell him so. But you can't do that more than about once a night.
Last week, I told a coach, "Coach, you asked me about the play and I told you what I saw. I'm not going to debate it with you."
About two weeks ago, I was working a game with a young coach who has his first varsity job. The fouls were 5-1 in the 1st quarter, which he pointed out. "Coach, we've called 4 fouls when they were taking the ball to the basket. Yn your end, you're shooting jumpers. The 5th foul was an illegal screen that I called when 43 set a bad screen for the 3rd time." He had no response.
Two minutes later, I call a shooting foul and the fouls are 6-1. Coach says, "You mean there's no contact on our end.?" "Sure there is, Coach. There's contact on both ends. But contact ain't a foul. Illegal contact is a foul." Again, no response.
So to be approachable, you have to be ready to answer whatever he asks about. And remember, for the most part, answer questions, not statements. You don't have to ignore statements, as you can respond with a "Okay coach, we'll take a look at it." They just want to be listened to. And if they talk to me the way they want me to talk to them, I have no problem with that.
Hope that helps.