That does not sound credible. Most likely the guy decided to jump and the dog did not let go.
Most people do not realize that dogs, espcially trained ones, are fairly easy to defeat one on one. It takes some nerve and sometimes the willingness to get mildy injured, but dropping a dog is not hard.
Yep, several years ago here in Sacramento, we had some drunken, drugged-out lunatic throw a police dog off a bridge, killing it. But you don’t have to throw them off a bridge. In fact, you don’t have to be very strong at all to seriously injure a dog. It’s only because most people are scared to death of being bitten that allows police dogs (especially the lone police dog) to be effective. I’m very thankful for that!