Can a 2500 lb sailboat be rowed with oars?

Yes. Oars are like levers. As Archimedes said: "Give me a place to stand and with a lever I will move the whole world." It may not be the best way to drive a sailboat (why not use the sails?), but in an emergency, or where there is no wind, it may be the only alternative to an outboard motor. Many sailboats are equiped with oars or paddles for emergencies.