1099 NEC

I received a 1099 NEC from our County Natural Resource Department as part of a grant program for habitat enhancement.  The money they paid me under the program was paid to another party for whom I contracted to do the work for me.  If I play along and complete a Schedule C (even though I'm not running a business) what are the ramifications versus checking "This is not money earned as an employee or self-employed individual, it is from a sporadic activity or hobby (This is not common)?  This statement is the truth....it was a one-time activity.

It was a grant....why am I paying self employment & income tax on this type of money?