Will Red Hat be nasty?

Not likely to happen because
Red Hat still has an extremely valuable brand name in enterprises.  If this were not the case, there wouldn't have been a 90% renewal rate for RHEL contracts.
Every piece of code that Red Hat (proper) has released, has been released under the GPL or LGPL.
Every interview that Matt Szulik and other Red Hat executives have given indicates an unswerving commitment to continue to release source code.