Software Recommendations has really just gone public—until yesterday, they didn't even have moderators yet.
When migrating to sites, you want them to be established first. Which means that they've been in beta for a really long time, or that they've gone out of beta already. If you migrate questions to an early beta site, you run the risk of having these questions lost forever if the beta is cancelled.
Furthermore, if a beta site cannot attract traffic on its own and needs questions fed from other sites, that's not a healthy growth either. That's why new sites are "left alone" during their beta period—to see if the idea of the site works out and whether it can survive.
Finally, Software Recommendations does not even have a proper definition of the topics they allow. You will notice that they don't have a real FAQ either. You want to give them time to establish some community norms first before dumping everything from Super User there.
What you can do is point people to SR in a comment, but you should also have them read this and this other Meta post. Not everything we close as off topic here for being a product recommendation question will be automatically on topic for SR.