I do wonder how the announcement went down. Can you imagine, you work for Red Hat developing open-source, then one day find out you've been sold to IBM?? funny when it doesn't haooen to you I guess, hahaha.
You should not assume there is a single binary choice feeling here. I could imagine a contract cleaner in Red Hat facilities checking out how well IBM pay cleaners, and deciding they prefer IBM, or go to another job. A vested knowledge worker, who is looking at both realizing their vesting state and acquiring a huge tax bill might have more than one view.
A new hire, who dreams of working in IBM Zurich might rub their hands with glee.
"it depends"