Colin Montgomerie's return to the top 50 continues to be dogged by a controversial ball-replacing incident at the Indonesian Open in March. The row was reopened on Sunday when senior pro Gary Evans criticised the Scot for playing his ball from the wrong spot after a weather delay.
And now Gerry Norquist, a respected member of the Asian Tour board, has told the Guardian he was "astonished".
But former world number one Nick Faldo called it "a load of codswallop".
The Englishman told the Daily Telegraph: "I don't believe everything I hear and only half of what I see."
Montgomerie qualified for the US Open in June courtesy of his 11th-place finish at the BMW Championship at Wentworth on Sunday.
But he would not have qualified without the ranking points he earned for finishing fourth in Indonesia.
Montgomerie escaped punishment for his actions but admitted his error and donated his prize money from the event to the Tsunami Appeal.
Despite some Tour members' "dissatisfaction" with the way the incident was handled, Tour chiefs believed they had drawn a line under the affair.
But Norquist added: "Giving his money to charity was a nice gesture but unfortunately all of this calls into question his integrity.
"Every one of us playing this great game of golf assumes that the guy you are playing next has the integrity to play by the rules. Any time that is called into question, then that is a serious matter.
"The guys who are talking about it are astonished by what happened. Monty has a lot of respect on the Asian Tour but this has been difficult. I guess we are all human. We all make mistakes."
O'Grady, however, said: "This has been dealt with coolly, and calmly and considered by 14 experienced members of a players committee with a very experienced chairman.
"They made a statement that we think finishes [it]."
Montgomerie is next set to play in this week's Wales Open at Celtic Manor.
The US Open takes place at Pinehurst, North Carolina, from 16-19 June.