Heh, funny that furball should mention that. I was just thinking about the original form of that question a few days ago, and I came up with an answer to that, and it applies here.
No, God cannot make a shield so broken that He Himself cannot nerf.
Assumption: That God is All-Powerful
Logic:
There are obviously two possible answers to this question:
1) God *can* make a shield so broken that He cannot nerf it
2) God *cannot* make a shield so broken that He cannot nerf it
Corollaries:
A) The corollary to point one is that a shield can exist that God cannot nerf. This implies an *external* limitation to God's abilities, i.e. that something *outside* of God Himself can be more nerfproof than His Almighty Nerfbat.
B) The corollary to point two is that a shield cannot exist that God cannot nerf. This implies an *internal* limitation to God's abilities, i.e. that God cannot create something stronger than Himself.
Given the assumption that God is All-Powerful, we can see that Corollary A implies that something *other than God* can resist His Mighty Nerfings. Corollary B merely implies that God cannot create something that resists His Mighty Nerfings. While both are clearly restrictions on God, A is clearly a greater restriction. Therefore, as we have assumed that God is All-Powerful, He must have as few limitations is possible. Therefore, B is true, and therefore 2 is true, and therefore God cannot make a shield that He Himself cannot nerf. (with His Almighty Nerfbat, or with anything else)
(Slightly more humourous than the original problem, but when stripped of its silliness, it does in fact perfectly solve the age old question of whether God can make a rock that He cannot lift)
