They already know whether the bottle was sealed. The officer knew when he handed him the bottle is was full. This is pretty obvious based on video.
Full bottles are generally sealed no? Why open a bottle and not drink it? Makes no sense. No bueno.
It’s gin. Hard liquor. Not unlikely to open it, take a sip, close it, and it still “looks full”.
And just being opened was enough for conviction. Doesn’t have to be not-full.
Oh, and I’ll be interested in the toxicology report. Alcohol was involved (even if simply a closed bottle) so it does suggest checking the driver’s BAC is a reasonable check.