Doncaster acknowledged that the short-term commercial impact of the decision was difficult to determine given uncertainty over contracts including broadcasting deals.
But when asked about an instant danger to clubs, he said: "I wouldn't have thought so. I'm not privy to the details of all member clubs' financial positions.
"The whole issue has an awful lot riding on it, there are some big numbers involved.
"The easy decision would have been to say 'yes' and protect commercial revenues. The clubs have decided to be bold and say 'no'."
There have been warnings made in recent days that up to half the SPL could face administration if the Ibrox club is not admitted to the First Division.
Doncaster was co-author of a document that claimed £16 million ($24.29 million) could be lost to the Scottish game if
"We've given as best a steer as we can but ultimately no-one can know what the position looks like until it happens," he said.
"Clubs have made a decision that has implications for their bank balances, certainly not a positive decision for their bank balances in the short term, but they have done what they felt they had to do and what many supporters wanted them to do."
Doncaster will now seek clarity on television deals. Sky and ESPN were due to sign a new £16 million annual contract this northern summer, although their existing deal still had a year to run.
"That certainly has to become clearer in the coming weeks," Doncaster said.
"There are a lot more twists and turns and decisions to be made."
Most if not all commercial partners, including the TV firms, have a clause allowing them to cancel or renegotiate if the Old Firm are not in the SPL.
Those deals were arranged amid speculation, mostly unfounded, that
But Doncaster defended the SPL's approach.
"Ultimately we're in a situation where we are selling a product and the market determines what it wants and what terms it wants that product," he said.
SPL clubs are now likely to end the 11-1 voting structure which has allowed
"We are where we are and we can only deal with this one step at a time," he said.
Scottish Premier League