Reading that interview, I don't think Townsend himself accused Maiden of anything. When Bruce said "with apologies to Pete Townsend", I think he was simply acknowledging a strong Townsend influence on the opening riff of that song.
The riff in question is not specific to any Who song; it's a standard chord progression (D-C-G) which appears in countless songs ranging from "Sweet Child O' Mine" to "Sweet Home Alabama". What makes it different from song to song is simply the arrangement (how the musicians play it).
Here's where I think the Townsend influence came from:
Reading the interview, Bruce said that he came up with the opening riff on an acoustic guitar. Townsend has a distinctive style of rhythm guitar, and it is particularly apparent on his acoustic work. I can imagine that if a person were to play CIPWM on an acoustic, it would very likely sound like Townsend. However, I think this similarity is lost in the full Maiden version. So as I implied above, Townsend may have strongly influenced CIPWM but there was no direct theft of any Who riffs.
