Schwartz said another team also was deeply involved in trade talks with the Chargers and close to a deal for Jackson.
Jackson, a restricted free agent who's holding out from the Chargers, had to sign a new contract by 4 p.m. ET Wednesday in order to play for a new team in Week 5. Now he'll have to finish the remainder of his three-game DUI suspension and serve a three-game suspension on the roster exempt list if he does sign.
Jackson sent a statement via text message to NFL Network and NFL.com.
"I just don't understand why (a trade wasn't completed)," he wrote. "They obviously think I'm a valuable player by asking for such high trade compensation, but why am I only offered tender salary?
"My agents and teams interested did everything to make it happen, but this organization stopped it. I just want to play football. It feels unethical and I am disappointed."
"All Vincent had to do was put his John Hancock on it," Schwartz said. "From a contract standpoint, it was done. There were two teams that were very involved, but the general managers I spoke to said that what A.J. (Smith, the Chargers' GM) was asking for was totally unreasonable. They said dealing with him was like dealing with 'The Lord of No Rings.'"
North County Times columnist Jay Paris dubbed Smith "The Lord of No Rings" after Eli Manning and Ben Roethlisberger, the other members of the Big Three quarterbacks of the 2004 draft class, led their teams to Super Bowl victories. Rivers, whom Smith and the Chargers acquired in a draft-day trade for Manning, has yet to make it to a Super Bowl.
"I wish him all the best," Rivers said at practice Wednesday, according to The Associated Press. "I'd love to get the opportunity to throw to him again, but if that's not the case, I want it to work out for him."
"It's been the same since we started camp," he said. "We get the guys ready who are here.
Jackson now must serve a three-game roster-exempt penalty if he signs with San Diego or is traded. Schwartz was adamant that Jackson wouldn't sign the Chargers' $600,000 contract tender.
"We're prepared to sit out the season, and that's always what we've been prepared to do," said Schwartz. The agent said he doesn't believe the Chargers have any intention of dealing his client before the Oct. 19 trade deadline -- the roster-exempt status makes the likelihood scant regardless.
Said Schwartz: "One GM told me, 'Neil, A.J. just wants to squat on your kid's rights. He never had any intention of trading him.'"
Schwartz said he and Jackson are disappointed with the outcome after putting in so much time seeking a trade and pursuing a resolution to the roster-exempt situation -- via the NFL and NFL Players Association -- but added: "Vincent is resolved to doing what he has to do, and he'll be fine."
If Jackson isn't on a roster for at least six weeks, he will not receive an accrued season toward free agency, with which he said he was unconcerned last month. His agents believe Jackson either will be an unrestricted free agent pending a new CBA -- and there is obvious uncertainty about what the new free-agency threshold will be -- or the Chargers could opt to use a franchise designation should it still exist, and that likely would ensure at least a one-year salary in the $9 million range.
Jackson, a sixth-year NFL veteran, made his first Pro Bowl last season. He has posted back-to-back 1,000-yard receiving campaigns, and he has 198 catches for 3,400 yards and 25 touchdowns in his career.
Jackson's original five-year contract expired after last season. But because this is an uncapped year, he would have needed six seasons to become an unrestricted free agent.
Unhappy over not receiving a long-term deal during the offseason, Jackson refused to sign the one-year, $3.268 million contract he was tendered as a restricted free agent. When he and holdout left tackle Marcus McNeill didn't sign their tenders by June 15, the Chargers were entitled to offer them 110 percent of their 2009 salaries, essentially cutting $2.5 million off the tenders.
Smith placed Jackson and McNeill on the roster-exempt list Aug. 20.
The Associated Press contributed to this report.