Is it OK to use employers stock images for side projects
I use stock images all of the time, and there is no reason that this issue needs to be discussed with a lawyer. Every stock image comes with a specific licensing agreement, and the agreement will explicitly state who can use the image and how it can be used. The OP needs to review the license agreement that applies to this image, and s/he should be able to determine whether or not the usage is appropriate.
If you are still not comfortable reopening the question, then maybe migrate it to Graphic Design SE?
ETA Since this is the meta site, I would really appreciate some feedback about the downvotes on this question. Not trying to be defensive...simply wanting to understand better why you all think that reopening or migrating the question are not better solutions than closing it would be.