Personally, I wouldnt feel comfortable selling a newly split anemone for at least 3 months after the split. That's just me though.
Anemones heal fairly fast, but the big concern is getting them back to healthy before doing anything with them.
Splitting uses an enormous amount of energy and reserves for the anemone and it can take time to get the anemone back to the level of where it was before the split.
A healthy anemone will be able to weather and transfer issues and parameter swings in a new tank (new to it, not newly set up) or during the transition to a new tank, (again, new to it, not newly set up).
A weakened anemone can have little reserves left and may not survive what a healthy anemone would shrug off.
Selling an anemone to someone that isnt 100% doesnt give them the best chance at success with the anemone, and anemone's are already among the most difficult animals to keep in this hobby....best to give people the greatest chance for success with them whenever possible.