[tottenhm]

I am very much a novice, but here goes...

I don't think the paper was trying to speak to truncation generally. Truncation is a weakening of the crypto by definition. (Reduce bits => reduce security.) It is easier (cheaper) to find a collision if one uses a truncated hash. That doesn't make it Dangerous or Safe; just quantitatively reduced.

If the authors are trying to establish anything, it seems to be, "Yes, collisions do matter!"