This really sounds like bs to me. Companies knew that all the time. BF4 released when, 2k13? Do you think that 4 years ago, lawyers didn't know about this? Well...
Also, modern combat games release all the time. What about Far Cry 5? Nearly 100 modern weapons ingame. Also Humvees and stuff. It's just about the money. They want to sell you a license. And big companies are able to afford it. Even to lock it (NFS held the Porsche license exclusively for at least 6 years.)
Bluedrake mentions how there are no longer HMMWV's in Squad, I went into Squad, checked it, nope... still there, it's just map-specific and the devs listened to the playerbase requesting the Oshkosh MATV
But I don't see how that would affect Sandstorm, as it's free promotion for gun-companies to have their weapons in games