The Utah Division of Purchasing and General Services investigated and rejected the allegations, and the attorney general's office, which looked at the only allegation that was potentially criminal, agreed.
BYU did not appeal, but two lawmakers asked the Legislature's auditors to take another look at the bidding process.
The resulting audit, shared with the Legislature's Audit Subcommittee on Tuesday, concurred with those earlier conclusions.
"Our review confirms their findings that these allegations do not appear to have merit, and there is no credible evidence of wrongdoing," the audit said.
Wright and Humpherys, speaking on their own and not for BYU, rejected the findings.
"They absolutely got it wrong," said Humpherys, who contends the USOE "put together" the U. team, overlooked that the U. team plagiarized a textbook sample in its bid and failed to meet other elements of USOE's request-for-proposals.
"It's very clear the Office of Education has a good ol' boys club and there are a lot of conflicts of interest," he said. "If this stuff went down at the federal level, people would be going to jail," Humpherys said.
Humpherys said the 2012 legislation that led to the state spending $600,000 for a homegrown textbook was his idea in the first place. He suggested it to Sen. Curt Bramble, R-Provo, and Sen. Aaron Osmond, R-South Jordan, ended up carrying the bill, SB217. Humphreys said he helped write the bill.
"If they had beat us fair and square, I'd have said, 'That team kicked our butt.'" Humpherys said.
Wright, whose utahmath.org website details what he sees as USOE's failures based on evidence such as emails he attained through Utah's open records law, said he's not inclined to drop the matter. "I will certainly talk to lawmakers," Wright said.
He rejected the notion that their complaint is nothing more than resentment over the U. team's victory. (The U. team also has a member from BYU's education college and from Utah State University.)
"I'm sure people will say that. That is one interpretation," Wright said.
Rather, he said, "We at BYU had been pushing USOE for years to improve math instruction. And this is just one instance of how they are not being responsive to what we consider good for math education in Utah."
Rossi, who is on vacation, said by email that Humpherys and Wright know their allegations are false but persist anyway.
"Suffice to say that in academia and most civilized businesses, most people are fired for making accusations with as little merit as those being made by Dr. Humpherys and Wright," Rossi wrote.
Brenda Hales, deputy superintendent of public education, said the USOE takes pains "to be absolutely sure there is no bias," as it decides among bidders for contracts.
Nonetheless, she said, Utah's math community is small, so USOE employees inevitably know or have worked with those who are part of bidding teams.
"I'm glad that the Legislative Auditor General found the same thing that I did, the same thing that Purchasing did, and the same thing that the AG's office did," Hale said. "I hope this will be sufficient to put it to rest."
Osmond, who sponsored the 2012 legislation, said Tuesday that he and Bramble were clear with the BYU team that it would be unethical illegal, even for them to craft legislation tailored for a single vendor. "We have specific ethics laws," Osmond said.
It often happens that a constituent or vendor with a good idea that becomes law is bested in the bidding process, he said.
Osmond said he found no problems with USOE's actions or its request-for-proposals and accepted the results of the investigations.