Personally I would prefer that knotsers delude themselves, and proceed with their soft-fork confident. Gets it over with faster and less contentiously that way.
Fortunately though, you're right. Regular (non bip110) Bitcoin nodes do not simply follow the longest chain- they follow the chain with the most cumulative proof of work. This metric is called "chainwork". It's basically the overall expected number of hashes needed to get to a chain of this size, after all previous difficulty adjustments.
If BIP110 activates without majority hashpower right off the bat, then legacy nodes will (eventually) follow the regular legacy chain as it accumulates more chainwork.
For BIP110 miners to "wipe out" and reorg the legacy chain in the future, as some have conjectured, they must not merely attract a majority of hashpower- they'd have to attract it and keep it for a very long time. The BIP110 miners would need to (on average) compute more hashes than the legacy miners did while the legacy miners had the advantage. The longer it took BIP110 miners to earn their hashpower advantage, the longer the BIP110 miners must maintain it for, to exceed legacy miners' chainwork and cause a reorg for the legacy nodes.
The rules of PoW favor whichever ruleset has more work put into it over time, not just whichever chain has majority hashpower in the moment. Think integrals, not derivatives.
Personally I would prefer that knotsers delude themselves, and proceed with their soft-fork confident. Gets it over with faster and less contentiously that way.
Fortunately though, you're right. Regular (non bip110) Bitcoin nodes do not simply follow the longest chain- they follow the chain with the most cumulative proof of work. This metric is called "chainwork". It's basically the overall expected number of hashes needed to get to a chain of this size, after all previous difficulty adjustments.
If BIP110 activates without majority hashpower right off the bat, then legacy nodes will (eventually) follow the regular legacy chain as it accumulates more chainwork.
For BIP110 miners to "wipe out" and reorg the legacy chain in the future, as some have conjectured, they must not merely attract a majority of hashpower- they'd have to attract it and keep it for a very long time. The BIP110 miners would need to (on average) compute more hashes than the legacy miners did while the legacy miners had the advantage. The longer it took BIP110 miners to earn their hashpower advantage, the longer the BIP110 miners must maintain it for, to exceed legacy miners' chainwork and cause a reorg for the legacy nodes.
The rules of PoW favor whichever ruleset has more work put into it over time, not just whichever chain has majority hashpower in the moment. Think integrals, not derivatives.