Is it possible that the child would eat at the table if he could watch Sponge Bob? Or, is it possible that the child would eat at the table if he had a placemat all about Sponge Bob? Is it possible that the child would sit and eat one bite of a favorite food (i.e., yogurt) then the TV turned on to Sponge Bob? If the child had a routine, scheduled time to eat at the table (timer set)... etc., would the child first sit and eat... then go watch his favorite show... Sponge Bob?
These are just a few things to consider. Of course.. every situation is different - we have to consider the environment - what is happening before the behavior and what does the behavior look like.. and what happens after the behavior that may be encouraging it.
However, after observing the targeted behavior of sitting and eating at school.... and observing the eating while running/walking/ & watching Sponge Bob behaviors... then it might be necessary to add visual boundaries and expectations for eating meals in the home. You can be very creative on how this is done to make it a fun and enjoyable experience for the child.
More later.... :)