If they join an open table and then refuse to start, in my opinion, that's a reportable offense.
It can happen every once in a while, if you realize that the table settings are not what you expected, or that you won't have time to finish the game, or you get a call. But if it happens repeatedly, that player is simply annoying you, and wasting your time (consider, for example, that you could have open tables at several games, waiting for opponents, and this action automatically closes all the other tables and forces you to reopen them).
A different thing is if the problematic player has an open table, you join them, and then they refuse to start. They have the right to decline to play with specific players for whatever reason. But if they join an existing table, they know who they're playing with before joining.
It can happen every once in a while, if you realize that the table settings are not what you expected, or that you won't have time to finish the game, or you get a call. But if it happens repeatedly, that player is simply annoying you, and wasting your time (consider, for example, that you could have open tables at several games, waiting for opponents, and this action automatically closes all the other tables and forces you to reopen them).
A different thing is if the problematic player has an open table, you join them, and then they refuse to start. They have the right to decline to play with specific players for whatever reason. But if they join an existing table, they know who they're playing with before joining.