First, nobody can document that Dr. Pierce “knew damned well” that whatever money he may have received from Bob Mathews was stolen: Glenn Miller knew that he was receiving stolen money because he asked; Dr. Pierce certainly would not have asked.
One of the co-defendants in the Ft. Smith trial, Bruce Carroll Pierce, who was convicted last month in Denver in the Berg murder, told the FBI that the group planned to give $300,000 to North Carolina Klan leader Miller, $200,000 to the California racist Metzger, $50,000 to William Pierce (no relation), $40,000 to Butler and an unspecified “large sum of money” to Miles.Another former Order member, Randall Radar, who helped train the commando squad in combat tactics, told the FBI that Matthews had told him he gave $300,000 to Miles.” [James Coates and Stephen Franklin, Chicago Tribune via the Spokane Chronicle, 29 December 1987]
Consequently there is no basis for Covington's insinuation that Dr. Pierce had some "immunity" or "arrangement" with the government.
Apart from personal animosities, it is obvious in this passage from Covington's novel The Hill of the Ravens, published in 2003, the year after Dr. Pierce's death, that Covington hoped to gain some followers by attacking the reputation of Dr. Pierce and his organization, which Covington called derisively "the Pierce cult":
"It is my understanding that before you joined the Party, both of you were briefly members of the Pierce cult.”
“Yes, that’s true,” admitted Ed. “If you found that in our files then you also know that back at the turn of the century, Pierce was all there was. The Northwest Migration was only just beginning to appear on the radar screen by the middle of the first decade. We were associated with the cult for less than a year, and we both immediately resigned when it finally came out after his death that William Pierce had been a longterm Federal government informant, as did virtually everyone else involved who had any sense of decency or integrity. The day after our resignations Brit and myself called the Old Man [i.e. Covington], explained who we were, and offered our services. He accepted. We have been completely devoted to the Party ever since.” [Covington, The Hill of the Ravens, p. 253]
* The only evidence that most of them had received any money was hearsay.