Not true. I've tried to make the push-feeds malfunction by using them upside down, tilting them in various directions, shaking them, jarring them, and anything else I could think of and they won't malfunction. I don't know where this started but I could never make it happen.
Well, you must not have tried very hard, because I was able to do it easily. Generally upside down, with the ejection side of the action down towards to ground, will do it consistently.
I did it with a .30-06, though. It may well be that a short action is harder to do this with, because the bolt isn't open nearly as wide.
That said, who cares? The old Pre-'64s aren't as accurate as many cheap modern guns, though they're certainly acceptable, and they're damned expensive old guns due to collector interest.
Furthermore, you can get a CRF action in a Ruger or a CZ any day of the week. And the 700 has been used as a military and LE rifle. The new Model 70s are "Pre-'64" designs, as well.
So, unless you're a gun collector trying to ascertain a rifle's value, the whole "Pre-'64" thing is kind of an obsolete howl, by guys who couldn't think of anything new to whine about in over 4 decades.