My impression from Rashi in last week’s parsha was that the halacha requiring a Navi to put a stamp of approval on the selection of the makom mikdash (Rashi on “l’shichno tidrishu”) was a one time event. The Navi was needed to identify the makom mikdash, but once selected, there is no requirement for further consent of a Navi to start building again.
R’ Ahron Soloveitchik in his sefer Perach Mateh Aharon is medayek in the Rambam otherwise. The Rambam prefaces his description of the mizbeiyach (Beis haBechira ch 2) with a historical overview – the mizbeiyach was the place from which the dust to create Adam was taken, it was the place Noach offered korbanos, it was the place of the Akeidah, and because of its great historical significance its location was known b’mesorah. Yet, continues the Rambam (based on Zevachim 62), the rebuilding of Bayis Sheni required that a Navi certify the location of the mizbeiyach. Even though there was no question as to where the mizbeiyach should be located, a stamp of approval from a Navi was still necessary.
I did a quick check of R’ Kalisher’s Derishat Tzion, which collects some of the correspondence between R’ Kaslisher and the Aruch laNer, R’ Akiva Eiger, and others regarding whether a mizbeiyach could be built to offer korbanos in contemporary times. The Aruch laNer raises an objection based on this gemara in Zevachim, but R’ Kalsiher seems to interpret the need for a Navi mentioned by the gemara as based on inexact knowledge of the makom mizbeiyach. Since we today have the kosel extant from Bayis Sheni (while those rebuilding Bayis Sheni had nothing), R’ Kalisher felt that we could figure out the makom mizbeiyach. I could not find any treatment of this Rambam in the letters, but I was skimming quickly.