You continue to file to file schedule C. Residual income from a former business is still self employment income*.
The IRS considers anything on a 1099-NEC to be self employment income. TurboTax (TT) aggressively steers you in that direction. If you try reporting the income as anything else, you chances of hearing from the IRS are higher.
That said, if you want to enter it as other income:
After entering your 1099-NEC, you will encounter a screen titled "Does one of these uncommon situations apply". Check the box "This is not money earned as an employee or self employed individual; it is from sporadic activity or hobby".
Checking that box will put the income on line 8 of Schedule 1 as "other income" .
*There is an exception for residual insurance commissions.