You can probably also disable NAT traversal, as you’re probably not interested in dynamic port forwardings or NAT hole punching.
I should also note that while there is nothing wrong with being cautious, syncthings connections are always encrypted and authenticated, so there is no real risk in running with default settings. Also, given the average crappy home router I usually wouldn’t consider the usual home network significantly more secure than the wide open internet 
. But as long as your local connections work, these settings are fine.