Sans Frontières MD Jonathan Lehrle told PRWeek that Peck had not been part of the "management breakdown", which he argued was the true cause of Bell Pottinger's.
Peck joined geopolitical specialist Sans Frontières last week as a senior consultant. The firm is chaired by Lord Bell.
Peck was an associate partner at Bell Pottinger, having worked with Lehrle at its sister firm Bell Pottinger Sans Frontières before a 2013 MBO combined the businesses.
In July, Peck was suspended by Bell Pottinger. The agency did not name Peck or the other suspended colleagues - now known to be Nick Lambert and David Bass - although it was confirmed that partner Victoria Geoghegan had been fired over the "inappropriate and offensive" campaign work.
The launch of Sans Frontières was announced in August last year, when Lord Bell left the agency bearing his name.
Lehrle, who had worked at Bell Pottinger from 2008 until the end of last year, told PRWeek that the company began trading in January.
Lehrle said that Peck was "not part of the management breakdown at Bell Potttinger... which is exactly where the fault [for its demise] lies, not in the Oakbay account", and said he offered Sans Frontières "great bandwidth and skills".
Management 'should have intervened' on Oakbay
Of Peck's role on the account itself, Lehrle argued: "Philip was a junior or mid-ranking employee. Blame sat with more senior people on that account... it should have been stopped or corrected by more senior people a long time ago."
Lehrle also said he was pleased, but not surprised, to see former Bell Pottinger staff quickly finding work since the business' collapse, saying: "Bell Pottinger was clearly doing something right."
Lehrle declined to name any clients of his new business, but said that the firm works almost entirely abroad, in particular in Africa and Asia, on political accounts and elections, on branding and crisis comms.
Alongside Peck, Lehrle and Bell, there are seven other staff currently at Sans Frontières, including Darren Murphy. Of those seven, two do not mention having worked at Bell Pottinger in their profiles on the agency's website.
Lehrle said Sans Frontières would "go back to the ethos of the original Bell Pottinger Sans Frontières of being very discrete about our clients", but said that the business would not go the same way as its forerunner.
"We like to think that we're better managed [than Bell Pottinger]," he said.
"We handled controversial clients in the past [at Bell Pottinger] and were subject to numerous protestations of outrage, but our finances were robust and we never really took a hit. I still believe that there are questions senior management need to answer, not actually about the Oakbay account, but how Bell Pottinger’s finances were allowed to get to such a precarious state."