Adrienne, the blonde who runs tests on Jason's body, removes his mask to get a look at his face (presumably at least somewhat out of curiosity). When Jason awakens, he probably realizes that someone has seen his face, and if we've learned anything throughout the series, it's this— Jason takes two things very seriously: his mother, and his looks. At various times during the franchise, he shows something along the lines of self-consciousness towards his disfigurement (Adrienne openly pitying him, even if it wasn't intended to be mean, probably didn't help his complex). So what does Jason do when he's pissed off at someone for looking at his hideous, rotting mug beneath the hockey mask? He returns the favor. He dips Adrienne's head in liquid nitrogen, freezing it nearly instantaneously, and smashes her face against the counter next to the sink. Jason, still holding her body by the back of the head, actually turns (what's left of) her face toward him and looks at his handiwork (a concave slab of featureless frozen skin and blood). Jason's no dummy— he knows when people are dead, and generally, even if they aren't, he doesn't care and just assumes they are. This is the giveaway that Jason was sending a message. "Oh, you think I'm ugly? You're about to look even worse."
The ship being named Grendel is exceptionally fitting. Both Jason and Grendel were monsters who dwelled in a lake, both came out and went on murderous rampages when people nearby were engaging in festivals and debauchery, and both had a strong devotion to their mothers. In the later films, Jason even shares Grendel's nigh-invulnerability to ordinary attacks. You could even go so far as to say that Jason Voorhees is the modern equivalent of Grendel.
Rowan's attitude of not showing any concern from being in cryostatis for over 400 years can be justified as being in shock. She is initially stunned by the news, though. Then Jason takes her mind off it.
