Charlie had no immediate solution to Ruby's poison and the formation inside her pineal gland. This made him realize the significant gap between himself and Fleur.
Although he had narrowly escaped the explosion thanks to the ring that Vera had given him, if Fleur sent three experts who were about to activate their pineal glands to Aurous Hill, Charlie probably wouldn't have any chance to survive. Even with Vera’s ring, he would only end up endangering her when the time comes.
As for Fleur, she