Maybe they felt there was no known or documented relationship between that editor and vi. Then again, they missed Bravo (which ran on the Alto) and Bill Joy has talked about its influence specifically.
Bravo is completely different. It's mouse-oriented, with proportional spacing and multiple fonts. It's the ancestor of Microsoft Word. Charles Simonyi worked on both Bravo and Word.
You can use Bravo as a programmer's editor, because the file format is plain ASCII followed by a control-Z, then formatting information. Alto compilers read the plain text part and stop at control-Z.