There is a youtube video about how brilliant and under appreciated the bass player for AC/DC was and really drove the music.
I know AC/DC is not Punk, but the bass parts are fundamentally the same, typically root based playing, on the beat reinforcing the drums and the guitar, but he did not play the root all the time, he reinforced the chords with 3rds and 5ths.
As long as you are reinforcing the drums and guitar you are playing Punk. Root, 3rd, 5th does not matter.
I know AC/DC is not Punk, but the bass parts are fundamentally the same, typically root based playing, on the beat reinforcing the drums and the guitar, but he did not play the root all the time, he reinforced the chords with 3rds and 5ths.
As long as you are reinforcing the drums and guitar you are playing Punk. Root, 3rd, 5th does not matter.