The message is seriously flawed in its logic or lack thereof. Much as with the legions at Zama thread, you simply ignore what we have and invent your own. Which is not to say that Caesar should be taken as the pillar of virtuous and accurate commentary that his Historum hagiographer, constantly hereabouts, would have him. I can only point you to the cogent posts of Olleus and DiocletionIsBetterThanYou. They say it all really. For this and the other thread.
However, GJC almost certainly made social, political and economic inroads into Britain for Romes benefit. By the time of the actual successful invasion of Britain, it is clear that Rome had local allies, who knew which way the wind was blowing. As an example, the docklands at London were built before the invasion, around 39AD iirc.
I do get facts wrong, but not in this case. As far as a military campaign is concerned, GJC lost, and thus the British are underrated.