Should I sign this 4506-C document??

I recently applied and was initially approved for a discover it card. However now I cannot activate my card until I sign this 4506-C "IVES Request for Transcript of Tax Return" document and supply Discover with 3 months of bank statements. Im fine with supplying the bank statements, the problem is I have never filed taxes because the majority of my income is non-taxable gifts. I have talked to Discover and they said its ok that I haven't filed taxes and the document is to verify that I haven't filed taxes. I have until next month to sign the document or they will close all my card accounts and I'm afraid that will hurt my score. And if I sign the 4506-c I also don't want to get pounced on by the gov. ...If they think I have all these unpaid taxes(which I don't of course). So I am willing to let the discover accounts close if absolutely necessary. What should i do?
any advice will be helpful!!