It didn't have to be "interpreted", the meaning was clear.
Kerry danced around the statement, claiming it was a bad joke gone worse,...
The explanation he concocted was one that only a stupid person would believe. Since he obviously expected the troops to believe it, he was, in effect, calling them stupid again.
Some otherwise-intelligent people can be infected by liberal blindness disease. Such people have no trouble accepting Kerry's "apology" despite the fact that it makes no sense.