I wouldn't read much into the Rice Digital + Gitaroo Man rumours as meaning that Rice Digital would be a credible source for Shenmue HD rumours:
-Rice Digital are practically owned by PQube. The website was founded by PQube's head of marketing.
-PQube are involved with Project Rap Rabbit. Note that a lot of the social media presence and push for the game is being led by Rice Digital, this is unlikely to be coincidental. The Twitter account for Project Rap Rabbit went live in April, one of the very few accounts that it follows is a project manager at PQube, who is handling communications duties for the game.
I'd interpret the Rice Digital Project Rap Rabbit posts as well-orchestrated marketing or PR rather than the confirmation of an insider rumour