The reason Clapper can still stand behind the letter he signed is clear to anyone who actually read it.
The letter says directly, plainly and clearly that...
THEY HAD NO DIRECT EVIDENCE that the laptop contents were part of a Russian disinformation operation. Instead they say that their experience tells them that it might be.
And that was plenty good enough for Politico and the rest to run with the false headline that the laptop IS
Russian disinformation.
See how that works?