Unless this is a bug, the text is misleading. Storm of Vengeance is supposed to be party friendly, and indeed does not seem to harm the party (protagonist and NPCs). However, I think it can turn HLA summons hostile, but don't think that it should (party friendly). Does Storm of Vengeance cause anyone else's planetar/elemental to go hostile?
Also, summon monster 3 (provides 1-hit distractions for Sikret's monsters ) will sometimes get winter wolves. The cold breath of these wolves will also make HLA summons hostile against the party. At most, it would seem more reasonable to me that the highly intelligent planetar would just kill the wolf if he thought the party caster had a lapse of reason rather than attacking all the party! (Hmmm, shall this LG angel kill a wolf or a Death Lord?) I wonder if something can be done about this type of scenario?