Sorry but I am having a difficult time following the events of the OP's story. First he said he had already boarded his confirmed LGA-ATL and then voluntarily deplaned which was met by well wishes from the other pax onboard. But then on the second paragraph, it mentions prior to boarding the LGA-ATL, he saw a direct LGA-CAK flight and made a dash from the LGA-ATL gate to the LGA-CAK gate and be chased by the LGA-ATL GA who wanted to and did re-allocate the OP's seat to a standby pax while the OP himself managed to get on the CAK bound flight.

So if the OP claims prior to boarding the LGA-ATL sector, he made a dash to catch the CAK flight and was successful in doing so, why would he claim to still have boarded the LGA-ATL and then ended up deplaning by himself?