Whoever first joins a dedicated server (also known as a standalone) counts as the host for that session, and has the ability to kick people. So that is not an issue.
Hacked tables simply means that the tables which tell the game everything it needs to know about the stats of ships, various AI settings and metric tonne of other things have been changed from the FS2 default. This may be innocent, like someone adding extra backgrounds to stars.tbl, or intentional and unavoidable until the new set is validated, as was the case for the MediaVPs for a long time and is still the case for the BP and WoD multi projects until they get their own little corners of FS2NetD to call their own. And these cases are why preventing hacked tables altogether would be BAD.
On the other hand, some players might indeed alter their tables for the purpose of cheating. But the thing is, they gets them nowhere: While people with hacked tables are allowed to play (unless the host kicks them), they stats will not be saved. So make an uberfighter that can slay anything 100x over and do just that in a mission? Your pilot will still have 0 registered kills. So that kind of cheating is already prevented.