Your miner knows before anyone else if they hashed a valid block, and thus, they can chose to not sumbit it, however, there is no direct gain for the attacker to do so, in fact, the attacker will lose money along side the pool and everyone else.
The one exception to that is hash rental companies such as NiceHash and MRR et al. They have in the past (several years ago) been accused of withholding blocks pointed at specific pools. Reasons were never hashed out (pun) but general opinion was to try and break the target pools as favors to some large players.
Then maybe 8 years ago there was the unintentional block withholding by Genesis mining who were using Slush. They had a massive hashrate and so when other Slush users hit a block Genesis got paid per their hash rate. One problem: Genesis was using a proxy to combine all their miners into one connection and that proxy had a bug in it that caused it to ignore all block found. Somewhere in the Forum there is a long series of posts about it.
Methinks it was Kano that pointed out the problem to Slush who then bitched at Genesis (who fixed the bug) but never returned any of the
BTC to the Slush users who lost out on earnings that Genesis got for doing useless work. With Genesis at the time being something like 1/4 of Slush's hash rate that was a rather large amount.