1) Reb Tuvya, it seems to me that what worries you about the Peshat of the Maharsha is that the words "Elu v'Elu" suggest that both heaven and earth were created from Tziyon, so how can the Maharsha say that the discussion in our Gemara relates only to where the creation of the earth commenced (and, therefore, there is no difficulty presented by Chagigah 12a, where there is a dispute about whether the heaven or the earth was created first)?

2) In fact, I can strenghten your question if we look at how the Gevuros Ari (by the Sha'agas Aryeh) explains the Gemara of "Elu v'Elu." He writes that it indeed means that both the development of the heavens and of the earth were created from Tziyon. Therefore, the pshat of the Gemara seems to contradict the Maharsha.

3) However, Tosfos (DH Elu) does not explain "Elu v'Elu" like the Gevuros Ari. Rather, Tosfos writes that "Elu v'Elu" refers to the middle and the sides of the world, and not to both the heavens and the earth. It follows that Tosfos is a support for the Maharsha, that the Gemara here is not referring to the heavens.

4) The Sefas Emes also appears to agree with the Maharsha. He points out that the verse which the Gemara cites (Tehilim 50:1) says, "And he called the earth...." According to this, the Sefas Emes writes that it is difficult to understand what "Elu v'Elu" means, since we are discussing only the earth. To resolve this difficulty, the Sefas Emes writes that "these and these" refers both to what develops from the earth and the earth itself. They are both created from Tziyon. The Sefas Emes is a support for the Maharsha because he proves from Tehillim 50:1 that only the earth is being discussed.

I hope I have managed to help make clearer how the Maharsha is consistent with the Peshat of the Gemara.

Kol Tuv,

Dovid Bloom