Picard also suggested a compromise to Dougherty in that there were so few Ba'ku that they would've gladly let the Son'a establish their own colony on the surface of the planet.
Dougherty summarily shut it down with saying that most Son'a won't live long enough to start benefitting from the natural radiation, therefore there was no other way but to go forward with the radiation extraction procedure that would render the planet uninhabitable, and his decision was final as Picard's superior officer and the Federation's official representative. I took it to be pretty much bullshit that the Son'a fed him, considering even the natural form of the radiation rejuvenated everyone from the Enterprise crew, completely regenerated Geordi's eyes in a matter of hours and cured whatever bad condition Sojef had (I don't quite remember because I watched it dubbed in Hungarian so I have no idea if it was just old age or something else). The only catch was that Geordi went blind again after leaving the area, but if the Son'a established their colony, this wouldn't have been a problem... also, Dougherty's "explanation" that most Son'a would need ten years to start seeing the effects of the natural radiation, to me at least, would imply that they would stop their own longevity, and more importantly, detox treatments after establishing their colony, but if they were indeed in such a bad shape, nothing would've stopped them from continuing those treatments (especially the detox one) for an interim period. But considering how hell-bent they were on avenging their exile that doomed them to an existence without naturally occuring immortality, I have a strong feeling that while they absolutely could've solved this without destroying the planet, they simply didn't want to.
EDIT: God, am I really defending Insurrection? What a day.