I don't agree with your claim on a supposed flaw in the philosophy. In the context of the Destiny universe with it's gods and space magic, and where killing things are actually metaphysically warps the universe to make you stronger, it is correct. On the subject of the final shape, we don't know if it's real or not, or if/how purging the universe of weak beings will help achieve this, so we can't say if it's just a rationalization, or whether it is an actual truth. If there is any flaw, than it has to be this lack of specifics regarding the final shape, and the mechanism to get to it (but it's a religion, so I'm sure they can hide behind "faith." Oryx and Savathun had an interesting talk about it in XLIV, Verse 5:2 — strict proof eternal). I don't think we're ever going to agree, so I think this comment chain will go on forever unless one of us gets bored :p