Silkworms are fine to feed. I raised my pac on a mixture of cricks, earthworms and silkies from a baby/sub-adult. Well developed and healthy after 1 and 1/2 years.
Also the silk worms in question are of the the african variety. There doesn't seem to be literature of other varieties containing thiaminase. The species offered normally from places like mulberry farms of the bombyx spp. while the dangerous variety is Anaphe spp.