They’re wrong.
If you ask SEM they will tell you (I know because that’s what I did) to contact Fide about the details. Fide ([email protected]) will tell you that the SDS certificates are accepted as long as they meet the formal criteria because getting the ALTE certification takes until 2029. If that were to change (SDS no longer meets the formalities) there will be a grace period of at least one year.
So, as long as SDS is on SEM’s list, and since SEM’s list is updated quarterly, you have at least 12-15 months during which the SDS certificate is accepted by SEM.
@axa mods, the SDS stuff is duplicate, there’s already this one. I suggest to close this (perhaps merge if there’s something worth merging) and let it slide into oblivion.