Schemes of the Scholar says:

"Book crest characters you control do not kneel to attack or defend during intriguechallenges. Raise your claim value by 1 during intrigue challenges you initiate"

Target character needs to kneel as a cost if he has to participate in a challenge. So, if character is knelt, he cant participate because he cant pay the cost for participation. Although, this plot says character doesnt need to kneel during attack or defense, so can he participate knelt already during intrigue challenge (theres no kneel cost...)?

From the rule book (p. 13 f): "Already kneeling characters may not be declared as attackers."

You would need an effect that specifically tells you that kneeling characters may be declared as attackers.

Rudeman said:

This is true for defending as well?

sWhiteboy said:

Of course. The wording for declaring attackers and defenders is exactly the same. Both sections of the rules have the "already kneeling characters may not be declared..." restriction in them.