Where in the announcement did it say they preferred using the...

Where in the announcement did it say they preferred using the roasting process? It doesn't say anything like that.
They simply are reporting the activities from the prior quarter in which a sodium sulphate roastbased flow-sheet was investigated.

Roasting Flow Sheet results:

"• Production of >99.5% battery grade lithium carbonate;
• High roast recoveries of 87% achieved;
• Reduced process costs – key reagent recycled;
• Minimal leaching of unwanted impurities, resulting in simpler precipitation of battery grade lithium carbonate; and
• Offtaker and end user testing – production of lithium carbonate samples underway"

Compared to LPD's L-Max results:
https://hotcopper.com.au/threads/ann-european-metals-signs-option-to-use-l-max-emh-plp-ax.2760784/
European Metals reports the key results of the Scoping Study and associated test work to be:
 98% of lithium recovered via flotation to concentrate
 99.5% of lithium extracted from concentrate via leaching
 Short leach time; 97.6% of the lithium recovered in only 4 hours
 99.56% pure lithium carbonate precipitated from a sample of Cinovec ore
 By-product potassium sulphate also successfully precipitated
 Estimated operating cost approximately US$1,500 per tonne of lithium carbonate produced (after potassium sulphate credit).

The results speak for them selves especially with LPD's recent announcements.