This is easy to explain. While it may not be THE explanation, I believe it is a plausible one:
a). When she started to sink, I panicked!! I was like, OMG, OMG, she is sinking!!! What should I do??? I decided to get help.
b). I was in a state of passive panic. I was just sitting there - not believing the reality of what was happening. My new wife! The woman I loved!! This was horrible. I just...couldn't....think.
c). I got scared - people were going to blame this on me!! I loved my wife! Tina was everything to me! I didn't know who to trust - I thought the police were out to get me! I knew they were going to want to make me pay for this accident that happened. I was emotionally destroyed, I couldn't respond appropriately to all those questions. All those police asking me all those questions - accusing me of killing my wonderful wife - I got scared - and confused. They were trying to say *I* did it. They were yelling and screaming at me - trying to get me to confess to something I didn't do.
d). It was wrong - and I am so sorry about that. I was just lashing out against my inlaws, who seems to be doing everything possible to help the police and nothing to help me! They were out to get me from the start. They just made me so angry - I didn't know what else to do.
OK, so finally someone is at least trying to come up with some kind of explanation that could potentially be used in court. However, there will be evidence against each one of these supposed defenses:
a) she was sinking - defense - to continue what Gabe said - faster than he could swim. Yet it took him only 10 seconds to swim against what he described as a very strong current to get to the line (his own testimony).
b) Passive panic defense - yes, this could be used in many cases, however, not in this one. Passive panic means that a person is unable to act. Gabe described many things he tried to do to help his wife, then in the end, he said he swam quickly to the surface, but his dive computer tells a different story. He actually took his time getting to the surface for help. So, the computer says he lying. Try to explain that one! So if he starts with a passive panic defense, he would be changing his story - yet again.
c) I got scared, and the police were yelling at me and trying to make me say - I did it - defense. Obviously, you did not watch Gabe Watson's video interview or read the transcript. They asked him questions nicely, they never yelled at him or tried to intimidate him. I'm sure they have even more video interview evidence to refute any such claim.
d) In-laws were trying to frame me so I lashed-out - defense. Tina's parents did not believe Gabe was involved for at least the first four months until Tina's father met with one of the people who was on-board the SpoilSport with Gabe and Tina. Gabe refused to allow Tina's parents to put a headstone on her grave and would not put one on himself for at least four months before Tina's parents began to suspect him. There is still no headstone on her grave, Gabe Watson will not allow it. Isn't this punishing the memory of Tina, the woman he supposedly loved? As a juror - I would want an explanation for this behavior. Better make it a good one.