That's been bugging me as well, and I appreciate you bringing it up because I think it would behoove us to debate that very question prior to sorting out what "recommendation" we want to put forward next session regarding Ternua (the Barony) after the Verdreths (the dispossessed).
I agree with the way you frame it as well: why would Sir Meden, of all people, give a fig what Sir Ewen thinks? On the surface it suggests that Sir Ewen has not been a topic of conversation between himself and his father, because the Earl was not exactly Ewen's bosom buddy (Ewen took the black rose without holding up his end of the bargain, he beat Curo in the race to obtain and retain a certain sword, he survived Curo's attempts to kill him by an assassination covered by arson - the last is apparently a favorite stunt among Earls!). However, that logic presupposes that Sir Meden and Sir Prehil are genuinely wanting Ewen's input and advice, which I think is a highly dubious proposition.
Some possibilities (not mutually exclusive), to be added to by others perhaps:
1. The two scions (or Meden alone) want to use Sir Ewen as a sacrificial lamb should a conspiracy on their part go wrong, implicating him in its creation.
2. The two scions are hatching a conspiracy, and want to feel out Sir Ewen by seeing how conventional vs. rebellious his suggestions might be. In this case, the actual recommendation from Ewen might not matter in the specifics, but seeing how far out of the box he is willing to go is the test, and if he is too conventional they will refrain from letting him further in on the conspiracy.
3. Alternately, they are aware of some other conspiracy afoot, they wish to counter it, and innoculate Sir Ewen against it by allying him with them before he is recruited to the other side. This is just an alternate version of their official story, where "conspiracy" is "the King's inclination".
4. They already have their plan laid out for Ternua and want to see if Ewen will interfere with it.
5. They really don't know what to do yet (as they are sort-of claiming), and Prehil has told Meden that this Ewen guy is a real fountain of ideas.
6. Meden is trying to smoke out a disloyal Curo, or Curo a disloyal Meden, and Sir Ewen will be used as a witness or nailed as a co-conspirator.
That's just off the top of my head. Anyone want to add to it, refute the probability of one or more, or vote for a favorite?
Other things we don't know? Who else opposes Harabor getting Ternua? And why does Meden even care about Ternua (his affinity is in the north)?