Not really surprised that MtC has a Tier 1 qualified product....

Not really surprised that MtC has a Tier 1 qualified product. It's been in production for years and would have sent off many samples for qualification work.
Suitability for EV battery production comes down to a lot more factors than lithia grade of concentrate. For example I've read posts in the past that when MtC was producing a grade of 5.6% this couldn't be used for batteries or hydroxide. Just shows a lot of naivete.
The market for primary carbonate from brine suitable for purification to BG is essentially in China, this includes Livent - through their Chinese facilities or possibly their newer US hydroxide one.
There was a line in the presentation that if SDV was purifying to Hydroxide in the future they could pivot their marketing to Japan / Korea. This suggests to me that prior to construction of a purification facility the key market will be China. Which makes sense considering that is where South American technical grade brine typically heads.
There will be decent operating margins and will reduce dilution of ownership with this strategy but obviously a technical grade product does not achieve battery grade pricing.