Can a sink faucet with a plastic spout be kashered?
If I am by someone else’s house that was told by their Rav that they can kasher it – is there makom to be makil?
Yes, there is certainly room to be lenient here.
Although there is an implication in Iggros Moshe, Yoreh De’ah 2:92 that plastic can’t be kashered, Rav Moshe writes explicitly elsewhere (Even Ha-Ezer 4:67; as pointed out to me by Rav Yehudah Spitz) that plastic can be kashered.
Some are stringent concerning this point for Pesach (and this could be the explanation for the stringency in the first teshuvah), there certainly remains room to be lenient, in particular for a faucet, where there is no actual contact between chametz and the faucet.