Be fair. I would be willing to bet that "ShellGuy" was advised by Shell attorneys not to issue an unequivocal endorsement of Rotella in motorcycles. Hence the "Check your owners manual" statement, which they say for questions about Rotella in cars and light trucks as well. It's all about avoiding liability ... or even the suggestion of liabiity.
That said, the Rotella forum has quieted down quite a bit.