Remember the exchange just after tower/BPC jettison during the Apollo 11 launch:
000:03:28 Armstrong: Houston, be advised the visual is Go today.
000:03:32 McCandless: This is Houston. Roger. Out.
000:03:36 Collins: Yeah, they finally gave me a window to look out. [Pause.]
Although the CMP normally sat in the middle seat during launch, on Apollo 11 Collins sat in the right seat and Aldrin was in the middle seat. So Collins' window was covered by the BPC.
The AFJ has this comment: [Although Armstrong as Commander has his own window through the Boost Protection Cover attached to the Launch Escape Tower, and Aldrin in the center couch can see through the hatch window above his head, Collins in the right-hand couch has had his windows covered up to this point.]