Do you not always fall backwards to properly take a charge? Are the only valid charges the rare occasion that a player is legit knocked backward off balance and didn't plan on falling? Of course not. Therefore, that's exaggerating contact.
As I said, that's part of the game and if you commit to taking that charge and the offensive player doesn't fall for it, so to speak, it can look pretty goofy and basically come off like a flop. But it was a defensive move you made that simply didn't work because the other player made a better move to counter it.
That's completely different from the blatant flops that are designed to make it look like the other player just attacked you. One is a valid basketball play, the other is not.