TT #60 · Parashas Noach · Fifth Aliyah · Passuk 9:23
Shem and Yefet took the garment, placed it on both their shoulders, and walked backward and covered their father’s nakedness; their faces were turned backward, and they did not see their father’s nakedness.
Torah Temimah points to Rav Yehudah (Berachot / related) — ervah of a non-Jew is still ervah for Shema.
English: “They did not see their father’s nakedness” — Rav Yehudah said: It is forbidden to recite Shema opposite a naked non-Jew… this teaches that they too are called “ervah,” as it is written “they did not see their father’s nakedness.”
Custom (ervah status applies even to non-Jews for purposes of Shema).
The nakedness of a non-Jew is still classified as ervah; one may not recite Shema facing it.