Welcome Ship's Computer
While certainly inappropriate, I'm not sure how you're saying the Prime Directive is being broken by Riker "fraternizing" with alien guests on the Enterprise
Regarding Biowarfare, I think you'd be hard pressed to find any reputable Doctor here in the United states, even in today's world who would engage willingly in Biowarfare to wipe out an entire species (Even one you are losing a war to), and it is illegal and against the code of War here in the United States. I can't imagine Starfleet would condone it (Don't get me wrong, desperate times call for desperate measures, and some leader would definitely consider and possibly act on a "Back room" operation to whip up a Bio agent, but, I don't believe it would be officially sanctioned or legal)
One Day I hope to be the Man my Cat thinks I am
Where are we going? And why are we in this Handbasket?