The operative parts seem to be
U.S. Space Force’s Space Development Agency ... is building a layered network of satellites known as the Proliferated Warfighter Space Architecture. It includes a Transport Layer of interconnected communications satellites and a Tracking Layer of missile-detection and early-warning sensor satellites.
“The studies will examine connecting commercial or other existing LEO systems to the Proliferated Warfighter Space Architecture to provide further resiliency by quickly moving broadband data between edge and main networks worldwide,” SDA said.
"a total of $1.6 million to the three companies" is chickenfeed, but might lead to a better position in bidding for the transport layer, I suppose. SpaceX is already doing some project called Starshield for Space Force.
In The Other Place, there was discussion of what it means.
I don't think SpaceX is interested in bidding SDA constellation work anymore, the head of SDA said so in an interview a while ago. The issue seems to be that SDA requirements means SpaceX needs a special bus for them, and there's not enough volume to make this worthwhile for SpaceX.
Chris Prophet suggests, then, that SpaceX might not bid on the Transport Layer but offer Starlink 2.0. He also pointed out
Believe SpaceX will use a new encryption software for their Starshield satellites supplied by the Aerospace Corp. It's too big a coincidence they both use same name, i.e. Starshield, and first orbital test came just before SpaceX announced they would develop a complete constellation. Hence Starshield should give SpaceX intimate knowledge of this new encryption standard.