Knost, the 2007 U.S. Amateur and U.S. Amateur Public Links champion, finished his first Nationwide Tour win at 12-under-par 268.
'The questions just kept going and going. It seems I answered the same thing over and over,' said Knost of questions about giving up an invitation to the 2008 Masters to turn professional last fall. 'After a while, it got really frustrating.
'People looked at it as The Masters, but that's just one tournament. Golf is not one tournament. I'm trying to make a future out of this game.'
Darron Stiles had a piece of the lead several times on the back nine, but was done in by three bogeys and a double-bogey on the final nine. He posted a 1- over 71 to take second at minus-11.
David Lutterus and Daniel Summerhays both shot 69 to share third place at 9-under-par 271.
Third-round leader Matt Weibring closed with a five-over 75 to tumble into a tie for fifth at minus-8. Weibring shared fifth with Rich Morris and Ricky Barnes.
Knost got off to a flying start with three birdies in his first four holes to jump to 10-under. He tripped to a bogey on the fourth at Hardscrabble Country Club.
After five straight pars around the turn, Knost birdied the par-five 11th. He picked up another birdie on the 14th, then drained back-to-back birdies from the 16th to gain a piece of the lead at 13-under.
Knost did himself no favors as he bogeyed the last. He headed to the scoring tent to sign his card, then had to sit for more than an hour and watch what happened with Stiles down the stretch.
'When I saw the wind was blowing so hard this morning, I thought maybe I'd have a chance,' Knost admitted. 'I thought if I could shoot five or six-under, you never know what could happen. I'm from Texas and I like playing in the wind.'
Stiles, who won his fourth tour crown here in 2006, wrapped birdies at two and four around a bogey on the third. He moved to 2-under for his round with a birdie on the ninth.
The 34 year old dropped another shot on the 10th, but he rebounded to birdie No. 11. Stiles fell back into a share of the lead with Knost as he bogeyed 13.
After Knost bogeyed the last, Stiles double-bogeyed the 14th to fall one back.
Stiles regained a piece of the lead as he drained a 18-foot birdie putt on the par-four 16th. However, he once again dropped behind with a bogey on the 17th. He parred the last to end one back.
'The whole back nine was Jekyll and Hyde for me,' Stiles admitted. 'I just didn't execute on a couple of shots when I needed to.'