If you want a long history of the town of Port Burwell, I recommend the Wikipedia article here. But long story short, Port Burwell was chosen because it was at the mouth of the Big Otter Creek, and would make a great port. In 1971, the park was established, but under the name of "Iroquois Beach P.P.". The campground and beach parking was added in 1986, with the subsequent renaming being a direct result.
Port Burwell is named after Mahlon Burwell, an important surveyor and politician who lived in the area.