Why did he freak out when I messaged him?

I literally added this guy on social media, he accepted the request. So he knew who I was (we were both laid off from the same company). Anyway, I inbox him one time for the first time. All I was asking was how he was and he answered with "Alright, just on the application grind" and I responded back but a few hours later I find out he just unfriended me. I am baffled as I didn't really do anything wrong.

Going back in time, when we had to talk in person he would seem nervous all the time, even though he was like upper management. Like he would mess with his socks and rub his hands together constantly and laugh nervously. He even greeted me a couple times but other times he would look down when he saw me. I'm so confused. I never even flirted with him. What's up with that?
Why did he freak out when I messaged him?
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