The “no bias” was used in regards to Comey only as far as I can see. It isn’t used in regard to Strzok and Page.
The excerpt I posted states that “several FBI employees who played critical roles in the investigation sent political messages.” If this comment was directed at only Strzok and Page, he would not have said “several”.
It could be that several of those employees aren’t specifically mentioned because they are potential subjects of a criminal prosecution.