I have read both the OP's posts and yours. Hers are very light on detail, yours sound very firm but are completely based on very heavy speculation and supposition.
You've stated that if the termination was just an excuse there would be no legal letters. This is wrong. Most companies or organisations or civil service department are swimming in lawyers. Sending a legal letter can be a paper trail and an arse covering exercise just as much as it can mean anything.
You've jumped to a conclusion about the amount of data. None of us has any idea how much is involved.
You've assumed his sideline, whatever it might be, is a conflict of interest. That's complete assumption/supposition on your part. You've also assumed he didn't disclose. Again, complete assumption/supposition on your part.
You've stated he sent all the info to the lawyers and didn't keep a copy. Again, we don't know that. When last updated, he was sleeping and the OP didn't know if he'd kept a copy.
You have no idea what the information he sent to himself is. It could be private medical data, it could be nuclear secrets, it could be a trademarked recipe for fluffy pancakes. There are material differences between the three.
You've said if he used it to benefit himself or if it causes them issues, he will face legal action. Again, you have no idea. Legal action is time consuming, expensive, risky and can be embarrassing. There are many instances in which it could potentially happen but doesn't.
You've said if he’s used the data he is likely going fo face a civil suit, and it will be costly. Again, you have no idea, nor do I.
You've said, it makes no sense that he would send himself lots of data so he could do his job on his own laptop in bed, it makes more sense he sent it to himself to use it for his side job. Again, you're supposing. You have no factual basis for this. People do all kinds of inexplicable or difficult to understand things.
You've said, if he’s done this, he’s not going to get work in this field again. If it was a ten year contract and it was nuclear secrets, probably not. If it was a six month contract and it was some kind of tech stuff, the odds are pretty good the company or organisation will be very happy for it to disappear without a trace.
You've said they will take all their assets when it comes to pay the bill. What bill? For legal action that hasn't taken place and might never commence? The OP's husband would have to either have really done something awful or have a lot of assets for it to be worth their while.
You've said the level of crying he’s done indicates he’s been caught in something bad. You don't know the man.
You’ve said she has no idea who else was involved and that you would assume plenty as they knew he’d taken the data. That's flagged up by the system in most companies. What does this have to do with anyone else?