Huh? Open source absolutely works with product management, their are tons of companies doing this today. OSS is a great way to market and up sell to SaaS
But then companies that make their money by upselling to SaaS really don't like it when Amazon comes along, takes the software, and undercuts them in the cloud. The company then scrambles to change their license to disallow that.
Wolfram in that sense is just being honest about their motivations by having it be proprietary from the get-go.
There are ways of preventing that like what elastic did. If wolfram honestly wants to be the sole computation language no one is going to pay for that all the time