You won't starve in Ferragosto, but the businesses more likely to be open are the ones you want to avoid anyway since they mostly cater to tourists.
Rome is also noticeably hotter than the coastline, hence a classic full day out wandering means literally soaking, not only in culture.

In a nuthell, go ahead if it's a day stop, not the end of the world.

But I wouldn't specifically plan it in Ferragosto for the sake of it.
And IMO this is valid for the whole Italy in that 2 weeks, since the crowd and prices where holidaymakers roam are simply not worth it.