It's also reported that the bomb contained a directional device, or shaped charge effect. It's possible, and even likely, the bomber was on the side away from direction that constituted the main direction of the explosion. There's still be enough impulse to to tear the bomber apart, but most or all of the nails, or ball bearing or whatever, would go the opposite direction.
Very possible (although shaped charges are tricky --- have dealt with them in the oil field (making perforations is casing); they are not for amateur --- perhaps this proves the point!)
But we would know if there is shrapnel or not.
"Holes in trees" sounds like insects to me. I've seen shrapnel's effects. It tumbles and weaves and wobbels. It tears stuff up -- it doesn't leave clean holes (although, in fairness I have never seen ballbearing shrapnel).
And, you know, it's all ballbearings these days.