Oh, no argument that they can be charged under those circumstances - that falls under the "conceal" part of the statute (although I'd wager most ADAs have better things to do than charge liars in small beans cases). Problem here is that is not what the OP posted - he doesn't remember anything, so isn't affirmatively doing anything.
And just to be extra clear, he can't be held in criminal contempt for failing to comply with a subpoena which was not properly served. (It appears that his was not, but I am not ready to conclude that for certain until speaking to his parents
).