I don't see why a prof would be reluctant unless they are not sure of themselves and think that the system is somehow zero sum. Maybe the student shouldn't want such a prof as supervisor.
And if you’re interested in a fully funded PhD position in operating systems/virtualisation/compilers in one of the nicest places in Germany (Bamberg, a UNESCO world heritage site) Germany, please get in touch - hard working and/or intelligent students wanted :). Master degree in CS/CE or a related discipline is required. Teaching is mandatory (5 hours/week teaching load during the semester).
Naive English or native German speaker with excellent knowledge of English preferred.
It really depends.