Increased supply stimulates demand by lowering prices. This would disincentivise poaching.
That only works if the fake product and the real product are indistinguishable goods. Fake ivory and real ivory are not equivalent; one has value as a status symbol. The cheaper fake ivory becomes, the more of a premium there is on having the real thing.
The same happens the rarer real ivory becomes, yet we see countries destroying ivory and otherwise banning it, making the remaining real stuff all the more valuable.
Think of artificial ivory as the "entry-level ivory". People who would never consider buying real ivory might buy fake ivory, because it is cheap enough. But then they grow so fond of fake ivory, they start to lust after real ivory.
That's the fear, anyway, and it's not total fantasy. Luxury car brands capture new customers with that exact model. The lowest tier of luxury car is even called the "entry-level" segment.
There are some big differences, but sure, they are reminiscent of eachother.
Experts aren't sure if it would be a problem yet, and are understandably concerned they might simply make the problem worse. Don't rule the concept out simply for vague association with the failing "war on drugs". "Should we flood the market with imitation ivory" and "Should we ban cannabis" are very different questions.
Given two options, both unknown on how they would impact the problem (and near impossible to test even if we did implement a change because we cannot isolate other variables), I would default to the one that increases freedom and decreases imprisoning others.
Also, indirect prohibition has shown to be failure time and time again, often being more harmful than not.
