I'm not sure what you mean by saying the arrangement is "a joke".
What I meant is that by the look of it, he just took the Rachmaninov score which is 95% piano solo and just added some chords and figures of the obbligato orchestra part. Can't have been a hard job. But really, what else could one do with this piece.
If I post my recorded performance of Pochacco's arrangement on my commercial website, and the arrangement is copyrighted, that creates a legal problem. Thus, I'd rather know for sure, but an extensive Internet search brought up no results for the identity of the arranger.
One would think that if this were copyrighted, then surely
1) A full composer name and publisher name would have been on the sheet
2) It would be for sale somewhere
3) Some info could be found on the web
I guess there may be no way to know for sure.