When SV miners (attackers) working on top of their previous empty block (and not your block) find a new empty block on top - they send it to a ABC/SV chain - all clients recognise that
this (their empty) block has more accumulated proof-of-work than yours and orphan your block (discard it).
The longest chain in Bitcoin software is defined as "having most accumulated
proof-of-work".
Even if you don't believe that the network would orphan this block - SV would mine in some time future next empty block on top of their own network block. ""
