Previous thread for reference:
Since son Natale listed his mother, Angelina Scalise, as his nearest relative in Italy on his 1909 manifest, and since his sister Filomena was born in 1900, it's my belief that Pietro passed away between 1899 and 1909, likely in Italy.
Not knowing Pietro's exact birth year is somewhat problematic but I'd still write a letter to the records office in Serrastretta requesting Angelina Scalise's birth and marriage acts
since we know she was born about 1868 based on the 1913 manifest. Her marriage act should include Pietro's age and his parents' names as well as Angelina's parents' names.