I’ve only heard about this in Creepy Pastas. Most of the tulpas I got to know and hosts I spoke to confirmed their tulpas are very loving, caring entities. The whole point in having a tulpa is creating something and give it freedom to express itself. Their purpose is not to serve, although they can do that. I think the reason why Sapien creates the servitor sigils is because servitors actually are meant to serve, so they are more suited to fulfill a task than a tulpa, since creating a tulpa only to give it work to do would be similar to enslavement.
I thought about solving this problem by creating a servitor that would feed tulpas, that would be a workaround, but ofc, a direct approach would be the best