That's my honest opinion and you are entitled to yours, fairly sure no one will ever know for certain. There's a journalist that went deep diving on this and came out with the same conclusion, from timelines to stylometric analysis, it doesn't add up to being Hal. He's just that guy who actually listened on the mailing list rather than be the snarky one where everyone else nods in agreement congratulating themselves how smart they are.
In the last years of his abled life, the man was getting involved in whatever cutting edge technology he could find, most of this is documented, nearly all of them failed, except for twitter and bitcoin. He's now cryopreserved, something that has virtually no chance of ever succeeding in the next 1000 years, yet...