Yet, your rabbi insisted that you wait until Shabbos to recite the blessing when a large congregation would be present. Great support for this ruling is found in Responsa Teshuvot v’Hanhagot (Rabbi Moshe Sternbuch, Orach Chayim, vol. 2:143).
He writes that the requirement to have a minyan for tefillah, or any other davar shebi’kedushah, is derived from Leviticus 22:32, “Ve’nikdashti betoch Bnei Yisrael, ani Hashem mekaddish’chem – and I will thus be sanctified in the midst of the Children of Israel.” Even if only six of those 10 present are actually praying, the minyan requirement is satisfied.
This is not the case regarding HaGomel, whose minyan requirement derives from “Vi’romemu’hu b’khal am – Let them exalt Him in the assembly of people” (Psalms 107:32). For HaGomel,one needs 10 men in addition to the one saying the berachah.
Rabbi Sternbuch goes even further, explaining that unless all 10 men respond “Amen,” the person saying HaGomel might be saying a berachah levatalah. He therefore advises that one take care to recite the blessing loudly so that everyone can hear and say “Amen” (followed by “Mi she’gemalcha…”).
I might note that, in general, this is a problem we often encounter when one is called to the Torah for an aliyah. Many people mumble the birchot haTorah, with the result that most people present are unable to respond properly. For an aliyah, one only loses an “Amen,” but for HaGomel, the very purpose of saying the berachah – to publicly thank G-d – is defeated if the congregation cannot hear the blessing and respond properly.
(To be continued)