What I want to ask is if we know for sure symbolic AI is a dead end and it doesn't worth to pursue that field.
From a practical standpoint Cycorp seems to have pivoted at least 10 years ago into providing knowledge and inference systems for clients. If customers are willing to pay them then perhaps we can conclude there is value in the technology. But again I'm not aware of any public examples to look at.
This is exactly the kind of thing that suggests they were nowhere close to AGI. Unless you think Palantir has somehow developed AGI too and kept it secret from everyone else.