Humans are selfish creatures. There is no way around it. Frisk is undoubtedly the most selfish creature they have ever met, and even then, they are far superior to the beloved human child that no one missed, that no one mourned except in absentia. Asgore wanted to see his wife, and his son. He had no room in his heart for anything else.

He speaks as though he has any leverage on them. As if his facts are absolute, and not marred by his own skewed priorities. Why it should matter to him, they do not rightly care.

It is immaterial.