By ALL accounts he was too ill for this to be plausible. Read that link on severe infections.
Are you Reeve's attending physician? I'm not. Maybe Reeve was too ill to make the call. The problem is this story started out saying he was in a coma on Thursday which would mean Kerry lied about a call on Saturday. We now know Thursday is wrong so a call on Friday or Saturday is possible. People can will themselves to do implausible things when they are gravely ill and by all accounts Christopher Reeve did that many times since his accident. The fact is there is a window of time when Reeve could have made that call to Kerry. People can hope otherwise but this story is weak and will probably only embarrass anyone pushing it unless Reeve's wife denies a phone call was made or someone comes up with some cell phone records for Kerry that shows he didn't recieve a call from Reeve.