No. Of course not. You clearly didn't read that correctly. (not to be mean) The entry itself says its blood heats up, causing it to grow weak. I don't see why this would make you think it's overpowered. In fact, this would really make Diglett underpowered.
EDIT: I agree with TheBlackEmpoleon, also, he's right. GameFreak does contrast with the game sometimes.
Source: Logic