The Cheque Centre PFA Scotland player-of-the-year candidate did his chances of landing the prize no harm at all as he took his tally to 27 for the season.
Griffiths struck after 31 minutes when he was allowed to cut in from the right to blast home at the near post. But St Mirren levelled after an hour when Portuguese striker Esmeal Goncalves benefited from some hesitant Hibs defending to level from close range.
The home side were ahead again when teenage striker Ross Caldwell netted just seconds after coming on as a 66th-minute substitute but two headers from Marc McAusland put Saints on the verge of securing SPL survival for the seventh season in a row after he netted twice inside five minutes.
However, Griffiths - who heads back to Wolves in the summer at the end of a 18-month loan spell - ensured he would have a queue of Saints fans willing to drive him south when he tapped home his second from Tom Taiwo's cross four minutes from time.
Fenlon said: "The first goal he scored was as good a goal you will see. He's in with a shout of winning player of the year. He's a special striker. He scores all sorts of goals as we saw.
"He's got a bit of a habit of scoring against St Mirren so they will be glad to see the back of him I suppose."
While the six goals offered up in Leith will have been lapped up by the 9,000-strong crowd, Fenlon was frustrated.
He added: "It was a nightmare. Where do I start? The positives. I thought we played well and our two young kids out wide, Danny Handling and Alex Harris, were different class.
"We created a lot of chances and I thought we deserved to win. But when you defend like we did you are not going to win games."