Rav Moshe’s Psak (based on the straight reading of most of his Teshuvos on the issue, as well as the testimony and practice of his children and many of his leading Talmidim) was that “Chalav HaCompanies” is Muttar mei’ikar hadin.
There are only two types of milk: Chalav Yisrael which is Muttar, and Chalav Akum which is Assur. There is no debate about this. The point Rav Moshe made (which, for the record, is echoed by the Chazon Ish) was that based on the Umdena created by government regulations, Chalav HaCompanies qualifies as the Chalav Yisrael mentioned in Shulchan Aruch, just as butter does not need supervision.
Nevertheless, he recommended that Baal Nefesh Yachmir. Most Poskim seem to agree that according to this Shita, it would not assur keilim. The Poskim who disagreed with Rav Moshe and held that Chalav HaCompanies is Chalav Akum hold that it is regular non-Kosher food, it assurs keilim, etc.
It seems that the OP could only have held like Rav Moshe, since otherwise there is not really any room to maneuver. In any case, the entire concept of “Shaas Hadchak,” and related issues (hefsed meruba, et at) is about the financial cost of maintaining higher than the minimum Halachic standard, even where such higher standards are universally accepted, and even (sometimes, specifically) when the food will be given to guests.
As a general point, the basic ground rule of Halacha, as established in Teshuvos HaRama, is that any Kula accepted in extenuating circumstances (Shaas hadchak, hefsed meruba, tzorech Shabbos/Yom Tov, etc.) must in fact be the Halachic standard, even if, under normal circumstances, we do not rely on it. In other words, no lenient opinion which is decidedly against the Halacha can be relied upon in any case. So those Poskim who allow Chalav Stam (even if only in Shaas Hadchak) by definition hold that it is Muttar mei’ikar hadin.
Also, the issue at hand was not one of insulting the host (they apparently have no problem eating together despite the different standards that they maintain), but one of cost. The guest wishes to avoid causing his host to spend more than he has to, and wants to know if in such a situation he may eat CS, which is certainly a Shaila for one’s personal Rav.