Apologies for the late reply; you are completely right, imagery like this is unacceptable and out of the question.
The offensive imagery has been removed. A first official warning has been issued and further actions will be taken if the user does not comply to our general guidelines from here on out.
Thank you for reporting!
EDIT: it has come to my attention that this is not the first committed infraction by this user. The next infraction will result in a ban.