You're another one having trouble thinking.
Getting early armor/magres does allow you to be extremely aggresive. The thing is that the brutalizer is just a way better starting item, because Renekton has a lot of survivability (lifesteal) anyway.

AHAH - PURE AGRESSIVNES! 1ST ITEM GUARDIAN ANGEL XDD

I agree with the comment above. If you got brutalizer first, then it would work. The problem lies with the fact that pumping out a guardian early game will let your offensive capabilities fall. Unfortunately, this could keep you in a tank position and less of a DPS position, posing a core problem to the necessary playstyle of Renekton himself. Brutalizer is essentially the core of Renekton. I do like the idea of an early Guardian though, even right after Brutalizer. Also, try to be a little more descriptive in your chapters, seems like not enough info to successfully build off of. Thats my two cents at least.

Switch brutalizer and guardian and then this is a fine build. I love the way ruthless predator works with the cleaver, so I suggest you get that before the second bloodthirster (you can still put an extra vamp scepter in between though).
Guardian Angel is less usefull in early game because the respawn time is short anyway.
Cheers.

I'm not voting +/-