I have no idea why he would state that. Aircraft have a forward and aft baggage compartment the amount of luggage has zero to do with aircraft balance.The term a pilot would use is actually CG(center of gravity). With no luggage the CG will be just fine. When luggage and cargo are loaded they are placed to maintain the proper CG splitting it between the forward and aft compartments as required. There is also the option to move passengers around to adjust CG.
As to the OP’s original issue tge routing was a bit complicated. Was this a cheap fare offered by the cruise line? With this type of routing I would want to get there two days early.