Yep. Java's garbage-collection is pretty good; I wouldn't expect any language supporting GC to do much better. So I would bet this isn't java-specific.
Note that Azul systems aren't just talking about "large apps like an office suite". They sell 54-core CPUs and java virtual machines designed to "scale to 670 GB of memory".
So we are not talking about optimising applets here, but systems that can run stock markets, large brokerage houses, etc. But such applications are also sometimes sensitive to latency. The old "stop the world" garbage collectors would be a real problem here, but even "incremental" collectors may cause latencies to some threads.
And (I haven't read the released code) perhaps they are more interested in moving some memory-management tasks from kernel to user-space. Things like large database systems often try to bypass OS behaviour and manage some things themselves (eg file caches) because they know better than the OS what the usage patterns are. Sounds plausable that a JVM may also have these needs.