"World Rugby takes responsibility for this oversight and has taken the proactive decision to stand Marius down to avoid any additional unfair and unnecessary conjecture."
The Irish camp had made a measured response to the issue of Van der Westhuizen's position on Thursday, with boss Schmidt insisting he was relaxed about the South African's role in Saturday's crucial encounter.
"That is a bit of a surprise," said Schmidt, of Van der Westhuizen helping out at England training this week.
"I'm sure in retrospect people are probably thinking it's not the best thing to do.
"I know Marius and I would have no hesitation in standing by his integrity.
"I don't think it will affect his decision-making and we'll stand by him as an official on Saturday."
England boss Eddie Jones had also earlier insisted Van der Westhuizen's neutrality should not be in question.
"What, are you questioning his integrity?" asked Jones, when asked about the issue.
"We went through World Rugby, which is the proper channels, so you are asking the wrong person."