Wow! They'll be wanting someone to net the sky and stop all birds coming over next! How unreasonable!
Can you move the table to the other side of the garden as a compromise? (Although I'd be more than tempted to get a few more feeders in myself, I must admit!) I very much doubt, however, that you are the only person feeding birds within flying distance of your neighbour's trampoline!! Might be worth pointing this out next time... My own personal view is that we need more bird feeders and less trampolines in the world anyway!! Which ones will do more long-term good...?!