"It's something that I'm disappointed about, but I should have thought about that when I was being a clown in the past.
"I thought time would be a bit of a healer, but obviously not," he said.
Guildford, currently recovering from a hamstring injury, is now targeting a comeback with the Waikato Sevens team in December.
However despite showing excellent form for Waikato during domestic tournaments last summer, he doesn't believe the national selectors will change their stance.
"I think that most doors are closed for me here in New Zealand from the higher powers at the NZRU.
"I'm just going to do my best here to contribute to Waikato through their sevens programme so that I can help the younger guys out," he said.
Guildford, who also played rugby in France with Clermont, also isn't ruling out another move overseas.
"That's something I'm looking into now that I've got myself right. I'm just keeping fit and healthy and maybe something will pop up in the UK."