The 'acceptable' level of experience is like religion and politics- many beliefs not as much hard fact. We could debate this infinitely and not bring anything new to an age old discussion. Fact is that some of the recent washouts at Spirit were not low-timers, quite the opposite. The most recent that I heard about was former Next-Gen 737 that just wasn't catching on to the Airbus.
A better way to steer this convo is why would a major resort to hiring these guys to begin with? I have my guesses, but I'd like some other input.