these guys probably talked with and turned down a spacex proposal in the past. these are multi-billion dollar businesses and that's basic due-diligence.

spacex has better leverage now, there's no chance in hell they went home with a better deal.

Yes but a reusable rocket will always be cheaper than a one-off rocket. They could charge twice as normal and still be overall cheaper.

do you think oneweb just bumped into spacex and they haven't considered them before?

evidently spacex's previous proposal had either a technical compromise they weren't willing to take, or it was more expensive than roscosmos.

now oneweb basically has been forced to make a deal with spacex and they don't run a charity, specially now that one of their main competitors is off the market.

I don't know how you go from there to say that oneweb will save money. spacex will make a ton of money, that I don't doubt.