Tamasa Puranas mention such matters. This is to satiate those who read it and not for us. Sri Ramayana quotes in certain places Rama was like Indra or Siva which are just examples to highlight the superior quality; it also states He was like Vishnu. It has never stated Rama adorned Vibhuti like Siva. The reference to Vibhuti is stated in many Puranas and even in Veda. Those are for the devotees of Siva. A Sattvic person should not adorn ash as per the ordains. One cannot read Adyatma Ramayana with these interpretations. The interpretations provided by our Purvacharyas are the basis for us. Veda and Puranas state many such matters which are not for us.