The British Pub Confederation (BPC), and Save the Pub group chairman Greg Mulholland, have told the Publican's Morning Advertiser that they would not meet Newby as part of his meetings with key stakeholders in the next month, following a letter to the group last Wednesday (27 April).
Mulholland said it was "absurd" to meet Mr Newby when the BPC had written to the Department for Business, Innovation and Skills making it clear they did not accept the appointment and make seek to challenge it legally.
Secretary of the BPC, and licensee of the Eagle in Battersea, Simon Clarke, added it was "inappropriate to meet with him (Paul Newby) at this time".
Clarke also cited Newby's interview with the PMA to draw attention to what he claimed was a "total misunderstanding of the concept of conflict of interest and perceived bias".
Clarke said: "In his own words he states "to object to his appointment is "a bit like saying a judge who was once a barrister representing criminals, can't be a judge".
"Of course a former criminal barrister may become a Judge but he would be disqualified, under the laws of natural justice, from presiding over a case where one of the parties was his former client. There is a lot case law on this.
"In a legal context that is a well known and common 'bar', surely Government, and indeed Mr Newby, are not suggesting the 'bar' in this context should be lower than that of even a High Court Judge?"
He also used an example of other government appointments, such as Baroness Fiona Woolf, who became chairwoman of the government's child abuse inquiry in 2009, but still had to step down because she had dinner with one of the individuals who could have been investigated.
He claimed that Newby's conflict of interest with Fleurets would make unbiased adjudication difficult for both sides.
Clarke said: "Assuming any adjudicator does the job right, inevitably his decisions will displease one or both parties, falling somewhere in between what the parties consider is appropriate, as a result the parties will look for answers to why things didn't go their way.
"Rightly or wrongly, the glaring answer for dissatisfied tied tenants will be that the adjudicator has favoured his former - and potentially future - employers, the pubcos. For a dissatisfied pubco, they will be suspicious that Mr Newby has leaned 'too far' the tenants way to try and preserve the illusion of independence."