Mehabit backfilling around supply lines

Hello everyone,
we are currently having a single-family house built by a developer. At the moment, the sanitary rough-in is taking place. In the coming days, EPS boards will be laid on the floors. I suspect that "Mehabit Typ S" is intended to be used as backfill around the insulated supply lines on the floor (filling the EPS recesses). Our companion from the Bauherren-Schutzbund does not approve of this, as the backfill in these narrow gaps cannot be adequately compacted.
What are your experiences? Won't the weight of the screed that will be laid later be insufficient? Mehabit is rather suited for more extensive applications, isn't it?
Thanks and best regards

well. it contains bitumen content so that the filling is relatively stable in the gaps once applied and does not slip away over the years due to small vibrations... we installed something similar and I have no concerns. there will still be styrofoam and 6cm of screed on top. I actually don't see any problem, but what does he recommend as a solution?