The Scotland international, along with team-mate Steven Whittaker, has objected to the transfer of his contract over to newco Gers and announced they will not report back for pre-season training.
Although Ibrox chief executive Charles Green believes the players are not free to leave the club for nothing and sign new deals with other clubs, PFA Scotland insists they are – and more are expected to head for the exit in the coming days.
Financial gain has been cited as the main motivation for players to want to end their time at the club as, being free agents, they would be able to command competitive signing-on fees as well as probable wage hikes.
Naismith, however, is adamant his decision is based on football reasons and football reasons alone.
With all 12 SPL clubs meeting on July 4 to vote on whether the newco should be granted entry to the top flight – and with Dundee United, Hearts, Hibs and St Johnstone having already announced their intentions to vote against Rangers' application – it looks increasingly likely top-flight football will not be an option.
High-level discussions are already underway which might allow Rangers to go straight into the First Division as opposed to starting again in the Third Division and Naismith says that lack of clarity is the reason for his decision.
He said: "The reason for my decision is, at this moment in my career, the uncertainty of what division the new company will be playing in.
"There's too much uncertainty there for me at this stage in my career to be waiting around to see where that is. I would hope to be playing at the highest level possible. I feel as though I would be getting held back if I was to move down divisions in Scotland to play."
Whittaker echoed Naismith's view that a drop into the lower leagues would be too damaging to his career.
"I didn't sign up to the newco because of the problems they are going to encounter and the sanctions which are going to be put on the club."
Naismith also insisted a lack of contact from Charles Green and information about the investors behind the Sevco consortium, who last week bought the business and assets of Gers, also contributed to his decision.
And he rejected suggestions this could be seen as opportunism at trying to quit the club and make more money by moving clubs.
He added: "The first bit of contact I had was last Thursday when I got an email and then my representatives met him on Friday.
"Part of the reason is that I can't transfer over to a new company when I've never met the person involved with it. I've never met any of the investors, I don't know anything about them. There is just far too much uncertainty.
"To be honest, the loyalty I had to Rangers I think was shown when I signed new contracts and took a 75% wage cut, when it probably wasn't in the best interests of any of the players. We did it because we had such a tight association with Rangers Football Club.
"It wasn't just about saving money, it was about saving jobs and we got that into our contracts that nobody would be made redundant.
"By doing that, it has given every employee at Rangers the chance to now transfer over to Sevco or walk away.
"We could have sat and said, 'no, pay our wages' and it probably would have brought liquidation much quicker and then people would have lost their jobs. As a squad, I'm very proud of my team-mates.
"I would like to think I've given my all for Rangers in every game I've played. I've shown how much passion that I have got for the club."
Naismith said he informed manager Ally McCoist of his decision and that he has parted company in an amicable manner.
He said: "The first person I spoke to after making my decision was Ally, the gaffer. I know he made a statement on Saturday.
"But all along, I've had too much respect for him to not let him be the first person to know. He's done brilliantly for Rangers in this current time."
Asked if McCoist urged him to reconsider his decision, Naismith added: "No, he understood. He thanked me for all the work I've done for Rangers and wished me all the luck in the future. He's held the club together in the last six months."
Naismith – who was the subject of a failed bid by West Brom in April – has no firm plans for his future.
He said: "I'll continue training and see what opportunities arise for me. I've not thought too far ahead."