My understanding of SegWit is that any non-segwit (legacy) nodes will see a SegWit output as an output anybody can spend (i.e. no signature required). That is presently high-quality since if the miner mines a block with a transaction that tries (illegally) to spend from that output, it will likely be rejected by nearly all of the nodes as a result of most nodes assist segwit and see that there is no such thing as a witness proof as a part of the transaction. However my query is how may a segwit output presumably be used to start with when segwit was simply launched and nearly all of the community the place non-segwit? Then anybody may simply spend the segwit outputs?

Segwit was activated utilizing . The precondition for segwit’s activation was that 95% of the hashrate was signaling readiness to implement segwit’s guidelines. Additionally, a majority of the opposite nodes had upgraded at that time. Shortly after activation, nearly 100% of the hashrate was operating a segwit-compatible model.