The Warriors sought leave to appeal today but NRL judiciary chairman Greg Woods rejected the request.
On Wednesday night, the three-man panel of Royce Ayliffe, Darren Britt and Bob Lindner took almost 50 minutes to find McKinnon guilty of spitting towards touch judge Brett Suttor. McKinnon was charged following an incident last weekend when he was placed on report by referee Ben Cummins.
McKinnon became the first player in NRL history to be suspended for spitting at a match official.
NRL prosecutor Peter Kite had earlier recommended a ban of between nine and 11 matches for what he described as a "reprehensible" act.
McKinnon will now miss the Warriors must-win clash against the Parramatta Eels this Saturday night.
Learoyd-Lahrs was issued with a seven-match suspension two weeks ago for a dangerous throw on Newcastle's Ben Cross.
Matai was originally given an 84-point penalty, but this was later increased to 112 points after it was revealed the NRL had forgotten to include loading from Matai's send-off in the Test between New Zealand and Australia in Wellington last October.