Nope. Just the opposite. It's the 48/24 'core' that always comes along for the ride, and could always be decoded. There was no full DTS 96/24 (or other extension of DTS) by DVD Audio Extractor decoding prior to the April 2017 release. Audiomuxer was the same story until July 2016.
I think we're both right because--and this is entirely my fault--we're talking about two different things. I, at my own peril, keep forgetting that lots and lots of people (maybe even the majority) decode the DTS to PCM as part of their process. I'm sure that in that context you're absolutely correct.
I, on the other hand, have always just "wrapped" the undecoded DTS in FLAC and I'm pretty sure that anything that could read the DTS stream would give me 9624 where it exists. I think any first-generation DTS-capable DVD player could pass DTS9624 to a decoder because, as far as I've ever heard, the players (assuming they're just passing the bitstream and not handling the decoding) didn't need to be updgraded/updated when 9624 came along.