It's not weird. Some people don't find it necessary to trumpet their particular beliefs or lack thereof to every passerby. I find it odd that you believe there is some nefarious purpose behind this. I mean, do you want the guy to come up, offer his hand and say, "hi, I'm an atheist. I thought you'd like to know."
No, I want him to say "I am an atheist and I refuse to have students hear that creation may have been created by a Creator".