Remember the PokéDex sometimes is wrong theory?
The Pokedex has noticeable places where it's wrong, or extremely hard to believe the information provided. Here's part of Magcargo's Dex entry from Sapphire:
MAGCARGO’s body temperature is approximately 18,000 degrees F.
That's hotter than the surface of the Sun. Does that sound accurate? Nope. Let's try Kadabra's Dex entry from Fire Red:
It happened one morning - a boy with extrasensory powers awoke in bed transformed into KADABRA.
Yeah, that doesn't sound very accurate either. How's that even possible?
The Pokedex also claims that Magneton's weight is over triple that of Magnemite's -- which doesn't make sense, considering that it's just three Magnemite stuck together.
So it's clear that the Pokedex makes a variety of errors, and not everything it says should be believed. Therefore, it's not a large stretch to think that the Pokedex simply was mistaken about Spoink.
TL;DR: It's probable that Spoink can indeed survive even if it stops bouncing, as the Pokedex has been known to make errors on other Pokemon.
Hope I helped!