Ma’amar Nasata Liraiecha Nes Lihisnoses (נתת ליראיך נס להתנוסס) 5711 – Perek Four -7 / Perek Five -1

Nasata Liraiecha Nes Lihisnoses 5711, Class Twenty Three, Perek Four (7) Perek Five (1).
Two stories, two Tzadikim, two levels.
Nochum Ish Gam Zu and his adage “Gam Zu LiTova” means he saw only revealed good, and that is how it was for him.
Rabbi Akiva (a little later in time and after the destruction of the second Beis HaMikdash and on a slightly lower level) said “Kol Ma DiOvid Rachamana LiTav Ovid” [whatever Hashem does is (ultimately) for good]; he didn’t see good in everything; but he knew and believed that ultimately it is for good (and if one is zoche they get to see it).
Question: why does the Rebbe use the expression Kol Ma DiOvid LiTav for Middas Hahishtavus?