Actually, it is implosions that happen slightly less often, not too sure about Snags.... The thing to remember is that Snag breakpoints are based upon the TN of the roll, not upon any specific roll-points.
Snags always happen when the result of a roll is 10 or more points below the TN. So, if the TN is 15, Snags happen on rolls of 5 or less. If the TN is 35, Snags happen on rolls of 25 or less....
One thing that this does mean is that the Snags for rolls with lower TNs will be less severe than Snags for rolls with higher TNs (which is part of what was intended)
BTW, thanks for that AnyDice writeup, I never was able to get the code for that figured out properly.... heheh