It was difficult to understand the pilots two announcement, but during the GA he said it was due to the cabin "not being secured", which I assume referred either to the fact that the crew member was standing, or that the passenger checks had not been completed. After landing the announcement was somewhat garbled, but the pilot apologised for the GA, stating it was "his fault".
As to the safety of a GA, it may well be a standard procedure that is followed, but it is still an abnormal event and occurs at time of high workload for the pilots, therefore however small the additional risk is over a normal take-off/landing, it is still an additional risk.