Would it have been right to commit genocide when alternative options were available?
If you were in the same position and had no knowledge of the out come where Lore would have taken over and almost created an even worse form of Borg.... it'd be difficult for any of us to come to the exact same conclusions.
In the end, I believe Picard made the right decision, though I could understand if the alternative was chosen.
Praxius, "in 'I, Borg', PICARD DID COMMIT GENOCIDE!
Picard had a chance to stop the borg and he didn't use it, knowing
that the borg are and will continue to kill BILLIONS, in an orgy of violence, death and suffering beyond comprehension...
Picard either used the weapon against the borg (using Hugh), destroying the hive mind, or he didn't, in which case he, too, is responsible for the death of BILLIONS UPON BILLIONS at the hands of the borg.
One can only choose the 'lesser evil' in this situation; there's no moral, 'white' choice.
Picard allowed the borg to endure, staining his hands with the blood of BILLIONS. Picard choose 'the GREATER evil', by far.
And why did Picard do this?
He did it in order to delude himself that, even in this situation, he made the perfectly moral, 'white' choice. So he took the choice that had the APPARENCE of being 'white', moral.
As for the BILLIONS the borg continued to kill, well, if Picard didn't have to see their faces as they died, he can keep telling himself they're not his problem, that their blood is not staining his hands, too."
About 'alternatives' - in the episode it was pretty clearly established that the paradox was the only weapon with realistic chances of working:
"Consider the crew's attitude towards this 'individuality' weapon - a jaded it 'may' do something.
Compare it with their certainty that the paradox will work.
The individuality attack was a long shot, had very low chances of succes.
Enterprises' crew knew that - and they were proven right by the individuality attack's failure to even scrarch the collective - only 1 ship affected out of HUNDREDS OF THOUSANDS OF CUBES the collective has? It didn't even slow down the borg!"