Frenchman Julien Quesne won the event — his first European Tour success — by two strokes courtesy of a course record-equalling 64 and a 17-under-par tally on the Aloha course.
Italian teenager Matteo Manassero (68) kept alive his hopes of making his pro debut at next month’s Masters by finishing second on 15 under.
Thornton celebrated his 35th birthday by carding a final round 68 for a share of 33rd place at five under. However, for the golfer living a short iron shot from famed Royal Co Down there was no celebration as his five-month-old son Ryan struggles with bronchial problems and with the funeral taking place of good friend Connor Mallon.
Mallon, the professional at Nairn and Portnoo, was found dead last Thursday in an Ardara hotel room in Co. Donegal.
Thornton has withdrawn from this week’s Hassan 11 Trophy in Morocco to be with his wife and son.
“Ryan is only five months old but he hasn’t been well for three months and it’s important now for me to be at home and helping out rather than be out here on the Tour,” said Thornton.
“Then with [the death of] Connor, it really puts golf into perspective.”
Shane Lowry shot a round of 67 for a share of seventh place at 11-under.
Meanwhile, Rory McIlroy’s two-week reign as world No 1 came to an end last night as Luke Donald won the Transitions Championship in Florida.
The Englishman needed a win at the Innisbrook Resort in Palm Harbour to reclaim top spot from Ryder Cup team-mate McIlroy — and he did just that by holding his nerve to win a four-man play-off.
Robert Garrigus, Jim Furyk and Sang-Moon Bae were the players edged out by Donald after the quartet had finished the fourth round on 13 under par.
Watching on TV, McIlroy tweeted: “Well I enjoyed it while it lasted! Congrats @LukeDonald! Impressive performance!”
Pádraig Harrington went round in par yesterday to finish the tournamnet in a share of 20th place on seven under par.