I'm not sure how seriously you were proposing this, but I would rank it's plausibility as being in the vicinity of Guam tipping over and sinking from the weight

I'm not sure how seriously you were proposing this, but I would rank it's plausibility as being in the vicinity of Guam tipping over and sinking from the weight of a military base. Inside traders are usually caught because they make profitable trades shortly before significant company events, or they're caught communicating with the tipper. This wouldn't protect from that. Once they're being investigated having a plausible reason for making the trade is mostly irrelevant. If you have no reason other than inside information for trading and just say "I felt like gambling" it doesn't matter. If they can't actually prove you had the inside information you're innocent. If they can prove you had illegal inside information it doesn't matter if you can prove that you made the trade for unrelated reasons. You're guilty.