"Funding secured" and "funding to be secured" are materially different terms. The point of "secured" is it's been bindingly, definitively agreed upon in a way that makes falling through very, very difficult.
His best defense is, absurdly, arguing a seasoned CEO doesn't understand what "funding secured" means. He might be about to inject enough doubt into a jury to avoid criminal charges, but I don't think that will outweigh the preponderance of evidence which is required for a civil judgement.
But that's the SEC's investigation. The deal with the article today, is that the DoJ... aka the FBI is beginning to get involved. This suggests that the FBI is concerned with CRIMINAL issues with regards to that tweet. Criminal penalties looks unlikely IMO, but who knows what the FBI manages to dig up?
In either case, the FBI looking into it doesn't look good at all. If anything, it helps solidifies the SEC (non-criminal) case of negligence.
That and if he's able to show he really thought funding could have been secured but fell through. IIRC we still don't know the full story on that.