Is this not a use case for an EntityIndexingInterceptor? The question is whether or not to provide something like a ManualIndexingOnly interceptor out of the box?

Not sure whether I like the flag option. The problem I see there is that the properties configuration is index manager/index name based. Settings are applied to indexes which is not the same as the entity centric "do only index entity X manually". In many/most cases index mananger/name maps one to one to an entity, but that does not have to be the case.

I'd either resolve this issue without any code changes referring to EntityIndexingInterceptor as a solution to implement this use case or I'd go one step further an provide a interceptor for this use-case out of the box.