Firstly, what different studies mean by a ketogenic diet is quite different. For example, it is very possible that a healthy ketogenic diet doesn't carry these risks, whereas an unhealthy high-meat ketogenic diet carries them.

Secondly, even if the risks continue to be present in psychiatric patients, the psychiatirc benefits could still outweigh the risks, and the risks could perhaps be offset in other ways, e.g. using a statin.