Singing of bhajans is very necessary even at that time. Why then did Swamiji put this restriction? Because your extreme love towards the deceased person causes your mind to be sad.
You are upset. Your heath is upset. Your house is upset due to death in family. May be at that time due to your mental state you may even abuse/curse God or Guru. It is not good. You may say, ‘Why did you take away my beloved? Why are you so heartless? Who says you are God?’
To save you from this pitfall, our ancestors put the restriction for at least initial three days we should stay away from chanting God’s names. But if your mind is calm and happy, if your mind is in complete control go ahead and sing bhajans. Chant Sita, Rama, Govinda, Krishna- no problem.
The restrictions were to prevent abuse of God/ Guru which is sinful for you. If your mind is good, if you sit next to the dead body and sing also there is no problem.
Who knows that dead body may wake up and join your bhajan session (Swamiji smiles..). This is not a joke. In Maharasthra they sing vittala vittala at all times. One man died. People were completing the death rituals like decorating the dead body all the while chanting- ‘Vittala, Vittala..’. As they poured cold water on the body, the man suddenly woke up chanting, ‘Vittala Vittala’. This is a real story.
(Q&A Trinidad 22nd July 2018)