Virgin probably uses a specialist company to do this for them That makes a big difference, and costs a lot of money.
Virgin doesn't use 'expensive
PR companies' in any of its ventures; its own
PR offices deal with this stuff.
Virgin is a commercial carrier, the MoD is not. The MoD may have very good reasons for not publicising the full details of an accident, including the names of people inviolved. Such conditions are rarely relevent in a commercial operation. The MoD will not suffer significant financial loss (other than compensatory loss) if it's perceived to be responsible for loss of life or injury. Virgin (Trains, Planes or Underwear!) could go out of business within days if it is perceived to be an unsafe carrier.
Gives something of an incentive to be good at this stuff!