Granted, the GAR has no available forces close enough to Mon Calamari to provide reinforcements on time, and that is why the GGA were called upon for help - they were the nearest army trained for amphibious warfare available to turn the tide at the Battle of Mon Calamari.
However, the GGA did not fare well against the Trade Federation's armies 10 years ago. Now, they may be fighting in their element but they are also facing the entire Separatist Alliance and a fellow amphibious species, the Quarren.
The Republic did not seem to perceive the GGA as merely a means to stalling for time until further reinforcements arrive - they were all the help that could come. Considering the points raised above, why did it seem that the Republic believed the GGA adequate for the job of turning the tide and winning the day?