It definitely can be interpreted to mean that the telemetry is opt-in, or that it is opt-out.
(“Opt-in by default” is a double positive, a less common sibling of the dreaded double negative)
(“Opt-in by default” is a double positive, a less common sibling of the dreaded double negative)
Opt-in by default: you are in You can’t not select opt-in: you are in
“Opt in , by default” would seem to mean you have to opt in, unless some unnamed external condition was met, so normally you would have to choose to participate… which is the opposite of this case , where to NOT participate you must, by default, opt OUT. And if you do not you are automatically committed to participate.