Completely speculative but this Tweet is a little random if you ask me:

Maybe he means giving them to an honest charity.

Wow massive speculation here. It could be, but I doubt it.

Well, there is no reason to not make a PSP emulator on the PS4, specially now that Sony is closing the PSP digital store in some places.

It's definitely a nod to BC for the PS2 but whether he's also hinting at PSP emulation is speculation. For him to Tweet that with less than a week to go to Playstation Experience is also a little suspicious if you ask me.

Yeah I see what you mean. Indeed it's suspicious. Plus as someone said, Sony just announced that they're closing the PSP Store soon... And Sony already built a PSP emulator for the Vita, maybe it was easy to remake one for PS4...

It could also be that Sony are going to offer ALL the PSP games for the Vita and so they only need the Vita store now.

If it's about emulation why would he want to give away his games as well?

Because they're not offering disc based emulation after all?

But why would he give it away then if the only way he can still play it is by buying everything new. Wouldn't that be a reason to keep the stuff?