Seymour's treble, added to a superb effort from prop Gordon Reid, saw the Warriors romp to a 38-16 victory in Treviso, after their play-off place had already been confirmed, following Ospreys' defeat to Zebre on Thursday.
The Warriors can still finish top of the table and will guarantee a place in the top two if Munster lose to Edinburgh on Saturday, or if they defeat Zebre on the final weekend of the season.
That would be an eighth straight RaboDirect PRO12 win and Townsend believes Seymour was the architect of victory number seven.
"He has been in great form all season," he told the Herald. "That's why he got in the Scotland team last year. In the last few weeks he has been outstanding.
"He had a great game against Ulster and he scored a crucial try against Ospreys. It's great to see him playing with so much pace and power and making great decisions. He scored two tries here last season as well, so it has been a happy place for him."
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