I don’t think that’s related; that circuit just leaves 2 of them unused. The oscillators themselves are the usual schmitt-trigger circuits:
(as a side note, I wish people would drop that silly “astable multivibrator” name, just call it oscillator since that’s what it is. Or if you insist on honouring the French inventors by using their silly “oh look at the harmonics, it must vibrate in so many ways!” name, at least spell it multivibrateur 
).