Yeah. As someone who grew up around the sea and loves Homer I always loved this description and it never seemed remotely strange to me. If you've ever seen the sea as the sun rises or sets it can seem almost syrupy and dark like a Burgundy even on a clear day. Likewise in cloudy days or during storms it can get very dark also.

And as you point out they would have been looking at wine in a cup (without transparent sides) so it would have just looked dark most of the time rather than particularly red.