While the latest version has Super Rolling fixed, it's actually rather easy to downgrade to an earlier version with it still available, and there's very little downside to doing so.

https://steamdb.info/depot/563561/manifests/

This page shows all the version updates with their manifesto IDs. These can be installed via Steam console commands.

Open the Steam console via steam://nav/console

Input "download_depot 563560 563561 7893380231726206941" (that's AppID / Depot ID / Manifesto ID)

This will download the August 20th update, the last before Super Rolling was fixed. For earlier versions, replace the last number by whatever manifesto ID the page offers.

Steam will start downloading the older version as a depot. When it's finished, the console will tell you where it output the download. From there, simply copy the files into the original directory of Alien Swarm Reactive Drop (make backups as you do).

You can play in online mode, you can host servers, your times will be posted on the leaderboards. I don't believe you can play with players on the latest version, but even this might be possible.