That pressure exists regardless. The more we relay it independently of them, the more plausible deniability they have that's all.

MARA will put junk in the chain that is relayed by <1% of the network currently so that isn't the factor at play here for the most part.

Delayed block propagation isn't really significant enough for miners to care. MARA did with the sub 1s/vb stuff but that's the world's least lucrative spam, and they seem to keep dipping into it anyway.