I don't know if true or not, but what I've read is that the outer skin should not be allowed to touch the meat, nor should the fillets be allowed to touch the cutting board where the skin had touched/rested. According to this the urea taste is on the skin and readily transfers to the meat if allowed to touch.
I've only cleaned one shark in the last few years. I followed this and did not get any urea taste that I could tell.
FWIW
BTW, I plan to be there if I can and I will have a woven rope with a bit of rebar tie wire inserted to stiffen it and hold it open for shark tails. No guarantees, either of my presence or the rope working, but Ill try.