If competition rules will require them, I'll put one in. It's all about safety!
Currently the AMA competition rules specify what, but (quite purposely) not how: leaving an airplane unrestrained with the batteries connected at any time results in a disqualification.
How you connect the batteries, how you restrain the plane, how you disconnect them, etc., are all left to the modeler.
In general people solve this with an arming switch on a full fuselage plane, or a dangling pair of connectors on a profile. They check the plane out in the pits (while holding on), then disconnect. Then they walk it out to the circle, connect, fly, and then either trust their helper to disconnect, or have their helper hold the plane while they disconnect.