From: Rabbi Moshe Sofer
To: Rabbi Tzvi Hirsch Segal
The dispute concerns whether the rabbinic decree suspending mourning for a drowning victim in unbounded water applies even when the victim is unmarried and there is no agunah concern. The Chasam Sofer validates Rabbi Segal's ruling that mourning should be observed for an unmarried victim, reasoning that since both sides agree mourning is intrinsically appropriate, one who is lenient about extending the protective decree to cases where it serves no purpose has legitimate authority to rely upon.
Source: Shu"t Chasam Sofer YD §344