Shapeways has made it clear that they honor DMCA takedown requests. And the reason they do not take
a more active role in investigating "dubious" content is probably that they do not want to be held responsible -
i.e. they can claim "save haven" status. So any repercussions from Sad Keanu et al. should be limited to the
designer (save for lost revenue at shapeways - but I doubt that memes and "fan art" make up more than a low
percentage of model sales).
And regarding the shorter copyright time frame for "computer-generated work", my understanding is that this
applies only to fully automatic renderings without artistic input or intervention, e.g. an X/Y graph derived from
a set of data points. (
generated by computer in circumstances such that there is no human author of the work
appears to be the wording in s. 178 of the UK Copyright, Designs and Patents Act of 1988 that Bill Bedford quoted,
and a 1992 amendment further qualifies that author of
a literary, dramatic, musical or artistic work or computer program
which is computer-generated, means the person by whom the arrangements necessary for the creation of the work were undertaken)