Hi John,
Yes, you're correct anyone over the age of 60 or that has a disability, by law, does not need to renew the Cédula de Identidade Estrangeiro. Like everything else the Federal Police do here in Brazil not everybody seems to be on the same page of the songbook, so it might be a good idea to remind them when you apply for the CIE that you're over 60.
When I applied I was quite worried about that too so I made a point of telling them that I doesn't need renewal. My CIE came back clearly marked "Classificação: Permanente Validade: Indeterminada", and so should yours. If it does not then you should not accept it, when they ask you to check it to make sure there are no errors (which BTW they are REQUIRED to do before they officially turn it over to you).