This combo, a dropped word and and added word suggests Bambi acted alone following a personal vendetta. But they have him on camera using a phone and that could spill the beans. The camera has a timestamp. The possible calls will only be a few thousand. Most records will be quickly eliminated. Phones have serial numbers that identify and hidden features like computers have. Bambi and company will have to know all about burner phones to evade detection. I do not think I know enough to pull such a thing off.
Brian Thompson had been getting phone threats. Forensic experts are going over phone records, and there is much we don't know.
If an anarchist group did it somebody may spill the beans. Your analysis is solid, but there are many possibilities.