If you mean the DC, it is equivalent to a creature with a 20 in the relevant ability score and the same hit-dice. That is a bit high, but they don't have hardly ANYTHING to back it up with. They literally can't deal hitpoint damage (ok, so maybe SOME GMs would give them an unarmed strike... a loop-hole I should probably close). Then again, if you throw a few suicidal goblins armed with war-scythes hiding and taking full defense it gets a lot nastier without increasing the CR hardly at all. A lot of it is probably due simply to the doubling of the hit-dice with each size increase. I think I noticed that effects with my Gut Snakes and some of my other organ undead.
If you mean the duration, after a certain point it basically might as well read "Until end of battle or removed". Speaking of which, Freedom of Movement becomes a standard buff at higher levels in my experience. That prevents Paralysis. Even 5 minutes (the worst case for the Colossal version) isn't going to do anything worse in MOST cases than run out the clock on some of the party's shorter duration buffs. Then again it could be fairly critical in situations where the encounter that included the spinal cords also raised an alarm that other enemies are responding to.
If it is the falling prone part... I guess that could slow you down, but it isn't specific to lower levels.