What guilt did he feel? He never did anything wrong. Nothing .
to the outside observer (us) he’s not to blame, but he is the one who basically de-equitized chuck and told him to take time off which one could say led to chucks death, and jimmy at the beginning of season 4 specifically called Howard out as being responsible, that season we were also shown how torn up Howard was in various scenes so he clearly felt responsible even though he shouldn’t feel that way, and now he’s on some privileged white self improvement journey “namaste”, he never stood up to chuck when he was alive, he could have vouched for jimmy and gotten him a joB but he didn’t, so he wants to make up for lost time
to jimmy Howard represents Davis and main, hhm, basically everything to do with jimmys past as being held down by chuck