Ok, I just thought of something in LBT TV Series. Chomper says that Red Claw had trouble seeing them if they hold still or something. No T-Rex in LBT up to that point had that problem. Also, Chomper seems to know Red Claw has this problem.
Well, in case you noticed, Red Claw has two different eye colors like one of them got damaged. If he had some kind of vision impairment, then that would explain what Chomper said. Also, if he has vision problems, it might also explain why he has Screech and Thud, as he might need them to be able to harass other dinos as they'd be able to get away from him without them being there. With them, they can help his harass and also help point him in the direction of others.
I doubt he's anywhere near as blind as Dil, but I doubt he has 20/20 vision either.
Just a theory I thought of. How Chomper would know that Red Claw has this problem, if my theory is right, is mystery, unless Chomper did something to his eye (maybe Red Claw tried to knock off a Leaf Eater, Chomper clawed him in the eye, and now Red Claw wants to wipe Chomper off the face of the earth for it. It would also parallel possibly to the original Sharptooth, who in addition to wanting to eat the Gang of Five, was determined to get them for the thorn in the eye issue.)
Also, as Chomper might have had a role in Red Claw's damaged eye, we can be sure that Red Claw is NOT the original Sharptooth as Chomper hadn't even hatched yet at the time of that incident in the first film.
Heck, if Chomper DID rescue a Leaf Eater by attacking Red Claw in the eye, the Great Valley would probably feel a lot of sympathy for him that, perhaps, they might not otherwise have given him.
As for Chomper's parents sending him off, Red Claw might have other pals somewhere and perhaps they didn't want to take on Red Claw directly, as would be their only option other than sending Chomper away. As they might have feared Red Claw might try something whenever they turn their backs, they probably, realizing that Chomper would be most miserable having to be guarded 24/7/365, have sent him off with Ruby with the mission to get help from the Great Valley, which, having been there, they might have told Ruby (Note: As Chomper was like a day old when he last left the Great Valley, he might recall the way, but Chomper's parents are adults and so would know the way and no doubt told Chomper and Ruby.
Of course, perhaps they decided they might need to tell them about the Great Valley but had them lay low with Ruby's family first and kept visiting them there often, not too often as it would be a giveway. Red Claw just happened to come on a day when Chomper's parents weren't visiting.