Was Algol 60 any kind of viable alternative at the
time?
The operating system for the Burroughs B5000 had been written in
Burroughs Algol. That punctured the widespread belief that OS's
were so particular to the hardware that they had to be written
in machine language. I don't recall how far Burroughs Algol
went beyond Algol 60, nor why Multics did not want to follow
that lead. ("Viable" is a slippery concept when choosing
among Turing-complete alternatives.)
Doug