How to hide a build in RTC?

Question

Yes, it should.
This looks like the same way I am hiding a Stream or a component in RTC, as I detail in "How to hide a stream from particular users in RTC source control?".

However, this thread doesn't mention visibility, only permission for:

requesting a build from a build definition
modifying a build definition

So it might not do what you want.

On the permission aspect:

Note that process permissions are looked up starting at the given process area and looking up its parent chain. Permissions may be overridden at the team area level, so different teams within the same project may have different permissions. Also note that the permissions are looked up for a particular user (i.e. the user running JBE or the Ant tasks), they're not defined directly for the engine itself.

For example, if you wanted to prevent team A's engine from processing requests for team B, then you would define:

two build users, bobA and bobB,

and two engines, engineA and engineB (associated with teamA and teamB respectively),

with bobA granted the relevant permissions in teamA, but not teamB, and the opposite for bobB.
When running the two JBEs, one would specify -userId bobA -engineId engineA, and the other would use bobB and engineB.

The build user(s) should also have permission to modify the build definition(s) for the relevant engine(s), since after the build request has been determined, it's the process area for the build definition that governs:

all further operations for the build (updating its state and status, contributing downloads/logs, etc.) and

the definition itself (updating the average build time once the build is complete).