New Zealanders Ximin Wang and Paul Weeks were among the 239 people on board.
Mr Weeks' wife Danica said although some books written about MH370 were "disgusting", at least Clark and Thomas contacted her before they finished writing The Truth Behind the Loss of Flight 370.
She said it was "irresponsible" to present any speculation as fact, but added: "I'm all for people doing research on this, because we've got nothing. We don't know anything."
However, she was concerned the authors had not spoken to Shah's wife. "Unless they've spoken to the wife -- and I understand she hasn't spoken to anybody -- I'd say their theory's flawed."
She felt sorry for Shah's family. "You're not only coping with losing your husband or your father. You're also coping with people, the world, saying it was him."
Meanwhile, Malaysia Airlines has extended its chief executive's contract for another 12 months. Ahmad Jauhari Yahya, who is also the company's managing director, is likely to keep the job until September 19, 2015.
Malaysian media say the airline's backers in the country's state finance sector were confident they'd restore the airline to profitability.
"When do you actually get fired for making bad decisions?" Mrs Weeks said. "There've been so many incompetencies."
Mrs Weeks said, for example, it seemed odd to hear only in late August about a phone call analysis that showed MH370 deviated from its path southward earlier than was previously thought.
"It took you six months to analyse a phone call?"
Mrs Weeks said she recently met three senior Malaysian government officials, including the deputy foreign minister. The meeting happened, she said, after repeatedly calling Malaysian government offices when the airline rebuffed attempts to communicate.
Mrs Weeks said she was grateful for the meeting -- but it yielded few answers. "They either aren't saying anything or they just don't know. But I begged them to give us an update on the investigation."
And she suspected the airline had now redeployed resources to investigate MH17. She said an airline employee recently told her: "Oh look, the investigation team's been busy with MH17."
The airline has acknowledged errors, and in a recent statement said an "urgency for change, evident through our continued poor performance" was obvious.
But Mrs Weeks said despite months of pleading and criticism, the airline had an attitude problem.
"Their handling of this has been just diabolical ... it's like we're all a big inconvenience, to be honest."
Mrs Weeks said families gained some relief from supporting one another. She said Ximin Wang's family had been in touch. The Wang family, of Auckland's Morningside, have made no public statements since March 8.
Malaysia Airlines could not immediately be reached for comment.
