No, it isn't.

PX on the freighter has for a while been a contentious issue. the outcome of negotiations on the subject, has been for all crew to voluntarily elect to sign a form which gives them permission to be PXed on the freighter. Many haven't, but many have; it is a big help for a lot of the based guys getting home.

I haven't, but I do zero PXing, as it is.

I'll be back soon, with an account of first-hand experience, which hopefully will answer someof your questions.