They're sending the certificate back because it currently has no fair trading value. Even though you paid 5 cents a share, who knows what the value of the stock will be once it re-opens, also they don't want to hold it waiting for the company to trade again. If they lost the cert, imagine the storm that would insue. I doubt any institution (or very few) would accept a certificate before WWF trades.
My hope is to get the certificate to RBC as soon as we hear that there is a resumption date.