First, as always, take anything from Hoopsworld with a grain of salt. At the same time, this isn't the first time we've heard Ray linked with Miami. They reportedly covet him, and it's easy to see where there could be some mutual interest.
Obviously, the Heat are the shortest path to a ring for Ray. In addition, maybe Ray wants to feel wanted. While the Heat have reportedly been after Ray for awhile now, the Celtics have been kind of lukewarm about his return. That, coupled with the various trade rumors (including the fact that he was in fact told that he had been traded at last year's trade deadline) and the benching, might leave Ray feeling less than desired.
In my mind, I can't hate Ray Allen, even if he joins the enemy. Players need to do what's in their best interests, and loyalty is a two way street. The Celtics have been very willing to explore moving on from Ray Allen, and it's fair for Ray Allen to look at signing elsewhere, as well. I certainly hope he's back, and maybe this is a story leaked by Ray's agent to get the Celts to trump Miami's best offer (likely $3 million per season, using the taxpayer's MLE). Whatever the reason, though, Ray Allen will always be part of our 17th championship, and will always have my respect.