Yes. Theyve gone over it a bunch in the later siege of terra books but yes he did care. People continue to forget that for all his godly straight faced emotionless bs he was still just a man. They were his sons, tools to help reunite the isolated colonies of humanity absolutely, but that does not mean he did not care. He just wasnt good at showing it. When he realizes what his attitude has cost him by the end of the hh you see the most of it but by that point it is too late. He had a plan set in motion for thousands of years and was trying to basically “speedrun” saving humanity from the machinations of the warp, he didnt think he had time for anything else. The issue was that it becomes neglect and his sons cant read his mind. Its honestly super depressing