Lynn initially said Gordon, who reported Thursday following a 64-day holdout, would be doubtful for this week.
On Saturday, the Chargers announced that they had activated Gordon to the active roster, making him eligible to play Sunday. The team could have kept him on the NFL's two-game exempt list until Week 6.
Lynn said Gordon looked to be in great shape during his two days of practice, but he has reservations about the Wisconsin product playing in pads for the first time and dealing with the mental part of the game.
"We understand that Melvin's been back for a day and a half, so we have to be careful if he plays, how much he plays and even if he plays at all," Lynn said.
For his part, Gordon said he is ready. The Chargers held a padded practice Thursday.
"I'm good, man," Gordon said. "I didn't really get to gauge myself like I wanted to, but like I said, if they call my number [I'm ready]. I've been grinding. It's not like I've been sitting around and I'm coming in overweight or anything like that. But it's not like I get a preseason game to get warmed up. You kind of get in and get right in the fire."
The Chargers head to Miami short-handed. Along with Jackson, receiver Mike Williams (back), kicker Michael Badgley (right groin), tight end Hunter Henry (knee) and tight end Virgil Green (groin) all have been ruled out for Sunday.
Gordon said he decided to return because he missed his teammates, and the holdout had not achieved his objective of securing a new deal.
He wanted a contract extension that would compensate him among the league's top running backs, like Ezekiel Elliott, Todd Gurley, David Johnson and Le'Veon Bell, who earn at least $13 million annually.
The Chargers had offered Gordon a new contract that doubled his annual salary to roughly $10 million.
"Nothing came out of it, so I try not to think about it," Gordon said. "Obviously there is no contract, so it's obviously something I don't want to speak on. All I can do is come out here and play ball and kind of let my skill take place and determine my future."
Gordon said when the Chargers suffered their first loss, against the Detroit Lions, he was surprised that he was upset. And when his team experienced the second straight loss, he felt compelled to return.
Those close relationships made it easier for Gordon to return. Gordon also said he chose to stay and workout nearby in San Diego because he was familiar with trainer Todd Durkin and still has a place there. It also allowed him to hang out with teammates during their downtime.
"They were cool about it," Gordon said about his teammates. "No one was hating or mad at me. They just said, 'Do what's best for you, know that we miss you and we'd be glad to have you back here.'"
Gordon also said the Chargers cut his fines in half. According to the league's collective bargaining agreement, Gordon can be fined up to $30,000 per day and nearly $330,000 for each preseason game that he missed. Gordon lost nearly $1 million in base salary from missing the first three regular-season games.
"It comes with consequences [of] sitting out," he said. "To think the fines would be completely washed away, I knew if I got in this situation, it wouldn't be. You do something against the rules, you pay the consequences, but I think they did what they could to help satisfy me and make me feel better about being out there."
Gordon believes there were not any bridges burned with the Chargers. They are the team that drafted him, and he kept a good relationship with general manager Tom Telesco during the process.
According to Gordon, Telesco is one of the first people he talked with when he returned Thursday. So a chance remains Gordon could stay with the team beyond this season.
"Business is business, football is football," Gordon said. "I've had conversations with Tom during this process; we've talked a few times. He definitely let it be known that he wanted me back and that he had no problems and he understood from a player's perspective. So that made me feel better about everything."
Gordon also said he has retained his same agents, Fletcher Smith and Damarius Bilbo.
"I was the reason I didn't come in," Gordon said, when asked about his representation. "They wanted me to come in, and I was like, 'No.'
"During this process, no one got really disrespectful. I think we handled it [OK], we just couldn't figure things out. But like I said, I think we've got more than enough time. It's not like I hate being a Charger. I love being a Charger. They changed my life, and I'm hoping we can figure something out from this point on, and I don't have to go to another team."