[jacalata]

that seems like a poor analogy to me. Try this one

Harry: I can't afford to do that

Tom: I don't know, I don't have enough info here to know if you can afford to do it or not.

Bob: Are you saying that Tom is lying, or that he doesn't know his own situation?

The big difference in this case is that while it is totally plausible for X and Y in your conversation to know literally nothing about Portugal, in my example it is not plausible for Harry to be unaware of his own situation without being an idiot. So when Tom 'withholds judgment' on Harry's situation, he is saying that evidence directly from Harry is untrustworthy - Harry is either a liar or an idiot. (I introduced the third person, Bob, as in this case Tom is Horvath and she is not the one responding to you, doubting Tom).

[patrickaljord]

This is a wrong analogy because it doesn't involve grave accusations of a third party (Portugal's economy in my case and github in the other).

[jacalata]

ok, try this

  Harry: John punched me     
  Tom: I don't know, I don't have enough info here to know if you were punched or not     
  Bob: Are you saying that Tom is lying, or that he can't recognise when he's being punched?