The threat of terrorism charges is completely ridiculous. There is no such thing as a charge of "international terrorism".

I guess they could have tried to get you arrested on charges of "interfering" with flight crew. From your description, it doesn't sound like they would win, but it would depend on the judge/jury.

I would just forget it and move on with my life. No point wasting your time with fools. Given that they made no attempt to actually arrest you, there is no real issue anyway.