Not the best idea...
It's an easy fix for a small problem, but it's not a good fix because the vent tube is so small that, unless it's inspected and cleaned out often, it becomes blocked by sea water minerals or waste...very quickly turning the vented loop into an UNvented loop that no longer has any ability to break a siphon. But because there's no dribble, it's "out of sight, out of mind" and ignored.Vented loops should have an air valve installed in the vent...a valve that only allows air INTO the line, nothing out. Air valves aren't entirely maintenance free either...they too require periodic cleaning and replacement.