Ruby and Chomper coming to the valley must have been an interesting time for Mr. Thicknose. He might have shared everyone else’s wariness of bringing a sharptooth and fast runner youth to the valley but since the gang might have explained their reasons and if there’s hostility to the gang, he might defend them out of gratefulness for how they positively changed his life. Once he started to know Ruby and Chomper, he likely became more trusting and fond of the pair. I can see Mr. Thicknose resisting the urge to bombard Ruby and Chomper with too many questions about what they knew in order to not overwhelm them and give them some privacy.
Yeah, he probably did his best to divulge the second hand information he was sure was right and what he suspected was nonsense. After all the tough work of parsing this information which gave him the ability to make educated guesses, he didn’t take too kindly to all of that being unwittingly shaken up by Littlefoot’s penetrating inquiries.