If someone stepped away from attending, they shouldn't be set to available. Unless it's a heated battle, there is no reason for anyone to have to wait for an hour for someone to accept their dragons. This is not impatience. This is standard expectation for sending dragons to another flight. Being set to available or online means that you are actively accepting dragons. If someone steps away, they would set themselves to offline or busy depending on their flight's attending rules.

There are multiple reasons for wanting another flight to accept your dragons quickly. The biggest being that not everyone has a lot of room in their lairs. In order to keep training dragons, some people need to offload the ones they've already trained. It's also easier to check for recording errors when your dragons are freshly recorded instead of a week later when most flights do their ticket check. Not everyone has an extra hour to just sit around and wait for someone to take their dragons.

If a big battle was going on, then yeah, a wait is not uncommon. For a flight that is solo pushing, an hour is pretty long. Seems like in this case there was an error on the spreadsheet, which happens. But the person asking was in no way impatient.