ANSWER:
A Muslim should be courteous as part of having good moral conduct and not say such things to them while they are grieving however, those who say they will get forgiveness even though they were disbelievers are speaking without knowledge and are ignorant as we know for certain that disbelievers will go to hell for eternity if they died as disbelievers. It is true that we don’t say that this particular individual is surly in hell as this judgement lies with Allah alone. However, we say that he was a kafir and we don’t give him any Islamic burial or treatment.