It's a bit ambiguous and depends on context, which is why I said 'at least in CS', since for whatever the particular topic is 'safe' and 'unsafe' is likely to have a fairly strict meaning.
In general you're right. For safety it's just that 'safest' implies some sort of practicality: the best - most safe - from a set of options. But the safest option isn't necessarily strictly safe.
(Say your dog's stuck on a roof on a windy day, you decide the safest option is scaffolding (safer than a ladder or free climbing), but it's not safe, you just insist on rescuing your dog.)
In general you're right. For safety it's just that 'safest' implies some sort of practicality: the best - most safe - from a set of options. But the safest option isn't necessarily strictly safe.
(Say your dog's stuck on a roof on a windy day, you decide the safest option is scaffolding (safer than a ladder or free climbing), but it's not safe, you just insist on rescuing your dog.)