פירוש על ברכות 38:4

A Bet Peras is a field, half a furrow in length and breadth, on to which crushed bones may have been carried by a plough which had passed over a grave. Contact with even a fragment of a bone would cause defilement. Peras is of doubtful etymology. It is explained by some to mean "half"; cf. Dan. v. 28. Wiesner, p. 49, connects it with πῠρά, because the corpse was usually first burnt. See also T. A.II. p. 490 n. 550.

Therefore the deference they show to the mourner does not involve disregard of the Torah.