[jfman]

They didn't.

That's your interpretation of "major platforms", it's a press release and use of the term has no legal standing. If Sky want to be snide in their use of the term excluding Virgin Media from their definition then they absolutely can, and did.

Some of Sky's portfolio is on Virgin, however it was entirely predictable that they didn't mean Sky Atlantic was coming to Virgin Media.

If those terms had legal standing they'd have to remove that news release as misleading. If you were to email and ask for a correction they'd laugh you out of town.