The 39-year-old believes that the Spanish international deliberately got booked against Real Sociedad so that he would be banned for Saturday's trip to the El Sadar.
"Muniain bottled it," Cruchaga told Cadena Ser de Pamplona. "He deliberately got the fifth yellow card as he did not want to come to Pamplona.
"He's a bottler, he is a very little man. It's amazing what he did last weekend. You can see it from a mile away.
"Anyone who knows football can see that he would have forced that fifth yellow. And then he started to complain about it. Well, if you don't want to come to Pamplona [then] get the fifth yellow, but then shut up [and] don't try to put it on the referee."
The 20-year-old attacker was born in Pamplona but chose instead to play for Los Leones.