It's less a "row" and more a straightforward capacity issue.
The ORR has produced a report detailing exactly how much capacity is available at Temple Mills, and the long and short of it is "some, not a lot". If an operator puts in a bid which only requires a small amount of depot space then in theory that could sneak in there and use that capacity, but basically all the serious proposals we've heard about so far (Virgin, FS Italiane, Evolyn and Gemini) are likely to be too big and need further depot investment. This isn't news to Virgin; they've read the same report everyone else has. They just need to figure out what they want to do about it.