This is certainly a pragmatic approach, however I believe PoS and staking is sub-optimal for rollups. Ideally, there should only be 1 sequencer live at a given time, or maybe 2 or 3. 100 or whatever is extremely wasteful.
A better approach is simply block producing auctions - which can be held in $OP or $ETH. The winning sequencers need to put up a slashable $OP bond. With some blacklists (whitelists at first) by governance so malicious entities are slashed and ejected.