In essence, yes, and him doing it as publicly as he did didn't help his cause (releasing his statement right away). To compare it to the Floyd situation again, David Gilmour, years later, said that Waters leaving the band officially allowed them to resurrect it on their own, as opposed to him staying and the band dying (since the others had no interest in working with Waters anymore, and vice versa). The big difference, of course, being that Waters never thought the others would carry on with the Floyd name without him*, while DT made it clear to Portnoy that they were carrying on without him.
*Had he, it's doubtful Waters would have left the band and let them do so, given what a bastard he was.