Well, they probably can't pull out more of their fleet:
It has been criticised for its poorly maintained and ageing fleet: 36% of its buses are not in use because they are awaiting repairs.
take all the older buses out of the fleet and resort to barebones service with the newer buses and let the city government suffer the political damage until they do something about it... not just wait for some disabled person to die...
Rome already has transport problems, and likely financial problems as well. Plus the transport company is not directly operating the company operating the buses (which is called Atac).
People tend to riot when they think they ale the low class and being left alone, I don't think that would improve the situation. It could make the "22 bus blasts last year" to shops lit, homes lit and whatever. Rome is not that stable. They have a new government, a migrant crisis, poverty in the south, and stuff like this.
buses around here arent exactly new but i've never heard of one bursting into flames... i can't fathom how it can happen more than once and not have the entire fleet pulled...