Not sure honestly and I can't read that article (paywall). I recently (just a few days ago) read official acceptance of the debate committee schedule had only been completed by Biden campaign. So maybe Trump proposed 4 but then hasn't accepted the actual invite yet?
The prez candidate who refuses to debate will lose several percentage points in the election, so that's not going to happen, they have to debate at least once. Trump will debate Biden.
If he does pardoning Snowden and making that into an issue is a brilliant move. That will sting hard.