This makes sense actually.
Let's have a scenario, is it not possible or just not implemented (sorry my ignorance):
I run knots and apply the same mempool filters to mined blocks OP_RETURNs (and drop just specific OP_RETURNs). Other knots users accept my pruned blocks because they personally don't need the data in those OP_RETURNS and assume it is spam (the same assumption they make when querying my mempool)