Keep it unused and clearly identify the sink as unsuitable for paint, plaster, grout or tool-washing waste. Follow the manufacturer's safe isolation advice and use an appropriate non-operating cover arrangement to prevent accidental entry.
What the observation tells you
Construction debris is not made acceptable by being mixed with water. Fine material can enter unseen, and a cloth pushed into the opening can become another obstruction if the appliance is started. Coordinate with everyone working in the kitchen.
A useful next step
If debris enters, report what it was and keep the disposer off pending advice. Do not grind it away or rinse a large quantity through to hide the incident.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.