Having worked with lawyers, this largely overstates the risk. Companies are happy to discuss, modify and sign new contracts every day.
All these contracts are "unchallenged in court", by definition, because they are entirely custom.
A lot of software licensing contracts for closed source have complex and restrictive clauses to prevent "renting" such software through SaaS or weakening limitations using legal loopholes.
Yet companies still sign such contracts.
Another type of custom and complex contract is employment.
Furthermore, companies sue each other every other day over contract violation around IP, copyright, trademarks, patents but also employment contracts, rent, building regulations, shipment delays, all of that.
The idea that a FLOSS license is some scary monster is propaganda.
The goal of such propaganda is to drive the FLOSS community to provide valuable software for free and with zero strings attached - aka free labor.