"Did you ever find out if a taxable grant reported on a 1099G could be claimed on a schedule C "

The amount gets included in the gross for that business using the Sched C. The grant that was for the business makes it part of business gross.

It isn't Linked.

It is reported as part of ordinary business income, unless you have the specific regulation or code that exempts it.

All of this is explained in this topic, and nothing about this has changed.