Calling a Rav Infallible is really disrepectful for the Rav. When you say or insinuate that a Rav is Infallible, someone who is looking to find a mistake he said, will usually find it without looking very hard. and then others will say the Rav is a phony causing people to disrespect the Gedolim.
better to be honest that gedolim are special people, who are not infallible and do make mistakes and people will respect that. Nobody expects them to be perfect unless they are put on a pedesel as and said they are.