I remember once seeing an article in a reputable newspaper in the USA which showed the (goy) Mayor of a town writing a letter in the Sefer Torah of a very Orthodox community (it was being written by the sofer, but as a ceremony, they were allowing the Mayor to write one letter).
I still cannot possibly fathom how this could be allowed? the community was an Orthodox one (which I won’t name) and I was as surprised reading the article then as I am recounting it now!
I tried to find sources on the question of non-Jews writing letters in a sefer Torah and found only one responsa to the effect that such a Torah would be rendered pasul.
Was there any basis for this community’s action?
I do not know any basis for the commuity’s action. It is possible that the letter was already written by a Jew, and the non-Jew was only given the honor of going over it, or filling in a small amount of ink that does not constitute an act of writing.
See Gittin 45b, which is the primary source for this question. According to one opinion cited in the Gemara, a non-Jew is fundamentally disqualified from writing a sefer torah, on account of his not being a part of the mitzvah (this is derived from a comparison to tefillin; see Ritva). According to another opinion, it is posslble that this disqualification does not apply (see P’nei Yehoshua), and the problem is only a problem of writing lishmah. If the problem is only writing lishmah, the presence of a Jew instructing the non-Jew in writing would render the writing halachically valid.
Rambam (Tefillin 1:15) rules that a non-Jew is fundamentally disqualified from writing tefillin, and the same would apply to a sefer torah. The rulingo of Shulchan Aruch (Yoreh De’ah 281:1) is not entirely clear on this point (see also Pischei Teshuvah 3, citing from Noda Biyhuda), but no authority permits the use of a sefer torah written by a non-Jew, and the discussion centers around whether the sefer requires genizah (because of concern of writing for the sake of idolatry) or not.
However, concerning the action taken by the community, it is possible that they felt obligated to give the mayor the honor, and arranged for his writing a small amount of ink in a letter whose form was already complete, so that the non-Jew’s writing would not constitute the writing of a letter, and would not create a halachic problem.