Yes, he can. I did put 共产党员 on the form. When interview, The off

Yes, he can.

I did put 共产党员 on the form. When interview, The officer asked many questions about it. He dig and ask the same questions in the different way...
Finally, we both laugh and I said, "no connection, no activity for more than 5 years..."

I got the US citizen approved in that interview day in 2007.

P.S. When I apply for green Card, I forgot to put 共产党员 on the form. I did in apply入美籍 form. Actually, the officer didn't ask me about it.

Hope it helps.