Nope. It only requires being able to read neighboring cells. It would make a privilege escalation attack harder but not impossible. DoS attacks would still be relatively easy.
Rowhammer is a memory corruption technique, so if you corrupt the right memory of a process in the right way then you can crash it; same for a kernel or hypervisor.
They are saying that privilege escalation is harder because it's really challenging to target specific bits to flip, whereas flipping random bits will eventually lead to a crash of some kind causing the service to fail which is effectively a DoS