Yes. We know that the unlaced boots were disposed of. The question then becomes, "What became of the laces? Why remove them from the boots prior to disposal?"
Possible answers abound, but since the boot laces seemingly cannot be accounted for, there's the distinct possibility that they were part of the commission of the crime: used as a garrotte, bindings, or simply contaminated in some way that required their disposal, separated from the boots they belonged to, presumably to help break the bond between boot and lace and between boots, laces, and Barry Morphew.
These are fair questions, IMO, as we know from the PH, because they are yet another point of departure from what we might call "expected behaviour" and the actions of BM as he went on his sequence of trash runs. Sure, the boot laces may be irrelevant, but the trouble he took to remove and then separately dispose of them suggests otherwise.
I don't quite grasp the "nexus" discussion, so will leave it alone.
