The POSIX subsystem was so crippled that it was unusable (no graphics or network). SfU was neither free nor included by default, except for one free version which also happened to be its last. Also at those times Linux did not have the market penetration that it currently has with Android.
What I heard was that they took advantage of every function that could technically be "implemented" by setting errno appropriately and returning an error value, rendering the subsystem useless while still allowing the box to be checked off.