If a card is removed from a challenge because of Highgarden, is it still considered to be participating to the challenge?

For instance if my opponent attacks with Maester Caleotte and I remove it from the challenge using HIghgarden (allowing me to win the challenge), is the Reaction of Maester Caleotte triggered?

Participating (RRG, p. 15):

"If an ability explicitly removes a character from a challenge, that character is no longer participating in the challenge."

If Caleotte is removed, he no longer "is participating" when it would be time to trigger his reaction, so the play restrictions and triggering condition for the reaction are not met (an the ability cannot be triggered).

Thanks for the answer.