Xebec was garbage, he failed with 3 future Yonko, and SHiki on his crew. The man sucks period. His only mistake was crossing Roger. He would still be alive if he never did that.
Roger died to fodder only after turning himself in, and dying from disease. He created a whole New Era of pirates on his way out. Roger is a true boss. Whitebeard also died as a boss as well.
To be a God Medalist, you have to be top dog, Xebec was never top dog at all, since Roger was roaming the seas back then, and in his prime without sickness.
Roger is the ultimate Cock Block, man was not as merciful as Luffy.