Frankly, not entirely. 
Your branching is your branching, I think what matters more is what is provided to users in terms of downloads and upgrades. Syncthing v2 is the thing we link to on the download page and what I think every new install should be. Upgrades are still not automatic for a couple of reasons, mostly that there are some behavior changes and it can take a while, so springing it as a surprise on people will probably not be widely appreciated.
I do think it’s important that there is a way for people who run syncthing-macos to get on 2.0 as we’ve been providing that upgrade path everywhere else for a couple of weeks. Waiting for 2.1, whenever that may be (really a factor of when a new feature triggers the versioning bump), doesn’t necessarily seem like a good criteria to me.
At the same time, I do not think you should auto upgrade v1 users to v2 at this time. Probably still not when release a 2.1. Maybe this is not possible to reconcile with the point above in your upgrade framework? It also wasn’t in for example the Debian/API packages, so we publish v2 there as a separate component which can be intentionally upgraded to, but is not an automatic upgrade.