Penguins are notoriously intolerant of people who overstay their welcome. But to be fair, if Newt was outdoors, his skin was most likely covered in that milky paste he excretes when under the sun for any amount of time, and the penguin would have mistaken it for the gelatinous ooze that contains their daily feeding of krill and squid. Or maybe the penguin simply remembered this photo and assumed it was being challenged by a hostile seal.

Sources: My Fox Phoenix