I assume your reference to Guide for the Perplexed 3:28 is to the last part where he writes:
Consider what we said of the opinions [implied in the laws]; in some
cases the law contains a truth which is itself the only
object of that law, as e.g., the truth of the Unity, Eternity, and
Incorporeality of God; in other cases, that truth is only the means of
securing the removal of injustice, or the acquisition of good morals;
such is the belief that God is angry with those who oppress their
fellow-men, as it is said, "Mine anger will be kindled, and I will
slay," etc. (Exod. xxii. 23); or the belief that God hears the crying
of the oppressed and vexed, to deliver them out of the hands of the
oppressor and tyrant, as it is written, "And it shall come to pass,
when he will cry unto me, that I will hear, for I am gracious" (Exod.
xxii. 25). (Friedlander translation)
While on the face of it, this may seem like ascribing emotions to God, we have to look how Maimonides explains God's emotions earlier. From Guide for the Perplexed 1:54:
Whenever any one of His actions is perceived by us, we ascribe to God
that emotion which is the source of the act when performed by
ourselves, and call Him by an epithet which is formed from the verb
expressing that emotion. We see, e.g., how well He provides for the
life of the embryo of living beings; how He endows with certain
faculties both the embryo itself and those who have to rear it after
its birth, in order that it may be protected from death and
destruction, guarded against all harm, and assisted in the performance
of all that is required [for its development]. Similar acts, when
performed by us, are due to a certain emotion and tenderness called
mercy and pity. God is, therefore, said to be merciful: e.g., "Like as
a father is merciful to his children, so the Lord is merciful to them
that fear Him" (Ps. ciii. 13); "And I will spare them, as a man
spareth (yaḥamol) his own son that serveth him" (Mal. iii. 17). Such
instances do not imply that God is influenced by a feeling of mercy,
but that acts similar to those which a father performs for his son,
out of pity, mercy and real affection, emanate from God solely for the
benefit of His pious men, and are by no means the result of any
impression or change--[produced in God].--When we give something to a
person who has no claim upon us, we perform an act of grace; e.g.,
"Grant them graciously unto us" (Judges xxi. 22). [The same term is
used in reference to God, e.g.] "which God hath graciously given"
(Gen. xxxiii. 5); "Because God hath dealt graciously with me" (ib.
11). Instances of this kind are numerous. God creates and guides
beings who have no claim upon Him to be created and guided by Him; He
is therefore called gracious (ḥannun)--His actions towards mankind
also include great calamities, which overtake individuals and bring
death to them, or affect whole families and even entire regions,
spread death, destroy generation after generation, and spare nothing
whatsoever. Hence there occur inundations, earthquakes, destructive
storms, expeditions of one nation against the other for the sake of
destroying it with the sword and blotting out its memory, and many
other evils of the same kind. Whenever such evils are caused by us to
any person, they originate in great anger, violent jealousy, or a
desire for revenge. God is therefore called, because of these acts,
"jealous," "revengeful," "wrathful," and "keeping anger" (Nah. i. 2)
that is to say, He performs acts similar to those which, when
performed by us, originate in certain psychical dispositions, in
jealousy, desire for retaliation, revenge, or anger: they are in
accordance with the guilt of those who are to be punished, and not the
result of any emotion: for He is above all defect! The same is the
case with all divine acts: though resembling those acts which emanate
from our passions and psychical dispositions, they are not due to
anything superadded to His essence. (Friedlander translation)
Here Maimonides tells us that whenever we speak of God's emotions we do not actually mean that God has emotions. We are simply referring to how God's actions would be described if performed by a human being. I.e. God is called merciful, not because he has the emotion of mercy, but because had a human being done the same actions they would have stemmed from mercy. Likewise we God is called angry not because he actually has the emotion of anger, but because a human being doing the same actions would be acting out of anger.
