In Act 4, Scene 3 in Macbeth, Malcolm deliberately lies to Macduff. What does this behavior and the reason for it, reveal about his character?

This is a rather curious scene in this play where Malcolm
shows his own character and ability to manipulate and test his subjects. In response to
Macduff's claims that Macbeth must be deposed, Malcolm presents himself as an even worse
king than Macbeth, saying, for example, that:

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But I have none: the king-becoming
graces,

As Justice, Verity, Temp'rance,
Stableness,

Bounty, Perseverance, Mercy,
Lowliness,

Devotion, Patience, Courage,
Fortitude,

I have no relish of them; but
abound

In the division of each several
crime,

Acting it many
ways.

He clearly exaggerates
his own "evil deeds," lying to Macduff deliberately to test his loyalty to Scotland
rather than to a specific person. When Macduff says that such a king should not be given
power, Malcolm says:

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Macduff, this noble
passion,

Child of integrity, hath from my
soul

Wip'd the black scruples, reconcil'd my
thoughts

To thy good truth and
honour.

Malcolm therefore
quite coldly has tested Macduff to work out where he stands and if he can be trusted.
The main function of this scene appears to be to assess the moral forces present in the
drama that are opposed against the evil of Macbeth, however, rather worryingly perhaps,
Malcolm shows himself able to manipulate others and test them for his own motives and
reasons, which could either be shown as a sign of political maturity or a sign of
potential evil to come.