 Tony promised Howard to allow Arno free market in the city as long as he didn't break any laws.Even though Arno constantly opposed Tony and even provided technology for criminals, Tony had not been able to prove his brother's illicit activities and opposed the idea to use his power as Baron to get rid of Arno.Also, Stark had tried to acquire Mobairu Yōsai Mechaniks to help Kiri Oshiro (who was the daughter of Rumiko Fujikawa) as well as to protect the company from Arno.