Objectively, very little probably. Non-java shops tend to avoid it because java codebases have a reputation for being relatively complicated. Java is a great language though and it may very well be the best cultural fit for the type of org that _actually likes_ salesforce. They also seem to be publishing a docker image, so it shouldn't be difficult for non-java orgs to integrate.

Python is more resource heavy than Java for CPU, but not for memory. I am pretty sure that Java is more resource heavy for memory.

Also, Java programmers have the habit of using excessive abstractions that don't solve real problems.