"We are now considering what, if any, enforcement action it should take based on the findings," a spokeswoman said.
That judgment would be made this week.
"Until that decision has been taken, and it is under active consideration now, we cannot release the investigation report as the information in it may become evidence if our decision is to prosecute," she said.
"Should we decide to prosecute, and I stress that decision has not been taken, the investigation report will then not be available until the conclusion of the legal proceedings."
WorkSafe was reluctant to reveal who had been spoken to during the investigation.
One of those injured sitting low in the stands at the trans-tasman rugby clash was spectator Cecilia Wang who was at her first All Blacks test.
The shrapnel broke her glasses, knocked her out and left her with a 6cm gash to her forehead. Two men sitting nearby suffered minor injuries.
Several weeks after the incident Wang described her fear of watching live matches and said she was suffering mental stress.
Van Tiel apologised to injured fans, saying he was shattered by what had happened.
"We're there to entertain people, not to harm anyone."
Van Tiel did not return calls.