The Dead Sea is separated from the Med and from the Red by ridgelines approximately 600 m tall (I think that info’s in the V piece, I just didn’t quote it, other than citing it from my fallible memory). So, IOW, that would be a big splash. :’) Also, boloid strikes on the oceans IMO are the mechanism for glaciation in the first place, with tsunamis being a pretty minor sideshow.
Although boloid strikes in the ocean might trigger glaciation, any major tsunamis could be the death blow to a developed civilization if the bulk of the educated and craftspeople inhabited the shoreline. With glaciation, they would have time to move out of the way. With a tsunami, gone in an instant.
I saw a recent show postulating that this is what happened to Crete. A Thera tsunami destroyed the Minoan ports, shipyards, and shipbuilders. When the craft which survived at sea came home, there was no one to maintain them property or build many new ones. Thus from 100 to 200 years later, the Minoan civilization went into eclipse.