Yes I can easily hear the guitar playing the quarter notes in the 6/4 measure. I can also faintly hear the cello play the dotted quarter note figures (along with the deep toms) in the 6/4 measure.

Yes, you could write the guitar part in 6/4 and the cello/ drum part in 4/4. But I have never seen it done this way before in my entire life. As a drummer, if I was to be given sheet music for this song, it would be presented in 6/4 with the low toms and bass drum rhythm notated in dotted quarter notes.

Although, like you said, it could be presented to the guitar in 6/4 and the cello/drums in 4/4. However, it would be a nightmare for a conductor to direct and the musicians to follow as the conductor would have to direct in 6 with one hand against 4 with the other!!