To be honest, to a point its true but to make that blanket statement that holding it by its jaw will break or dislocate their jaw is nonsense. Ive held a ton of large fish and not once has it broken or dislocated its jaw. That concept came about from people holding it by its jaw and trying to angle it more horizontally without supporting the belly. If your holding it vertically you will be fine. If you want to hold it horizontally you will need to support the belly.
For me its all about making sure you handle the fish with wet hands and getting it back in the water as soon as possible and making sure it swims off ok. Part of achieving that is making sure you have everything you need easily at hand. Pliers, camera, etc should be readily available so that as soon as you get the fish out of the water you do what you have to do and get it back in the water asap. If it has a hard time swimming off then dont let it go. It is important to keep it upright and give it a few minutes until you are sure its ready to go.
For me its all about making sure you handle the fish with wet hands and getting it back in the water as soon as possible and making sure it swims off ok. Part of achieving that is making sure you have everything you need easily at hand. Pliers, camera, etc should be readily available so that as soon as you get the fish out of the water you do what you have to do and get it back in the water asap. If it has a hard time swimming off then dont let it go. It is important to keep it upright and give it a few minutes until you are sure its ready to go.