That year-ago presentation cited different configurations that would be compatible with I-4 BTU, either preserving the central 44' rail ROW or not, and how that effected the costing.
Absolutely understand things have changed in the last year, but Brightline has publicly announced in the last month not only the transfer station with Sunrail (so Sunrail traffic can switch to OIA or OCCC or...) but also a stop somewhere near WDW property. I'm only saying if there is still going to be, their words, "an alternative station will be located near the original Disney Springs site, albeit not on Disney-owned land," then Grapefruit-vicinity seems to make the most sense. Much longer pedestrian bridges & pathways from I-4 median to any other location of interest in the area.