There is a very similar snippet regarding when scopes are active for all EJBs in 6.7.1 and 6.7.3. Neither appears to directly address @PostConstruct, though 6.7.3 does address @PreDestroy.
It makes sense to me that application scope would be active during @PostConstruct, but that request scope might not be as @PostConstruct might be called outside of a business method invocation. I believe 7.2 states that lifecycle callbacks are not business method invocations.
This is a slightly more generic version of
CDI-219, which specifically addresses request scope in EJB @Singleton @Startup @PostConstruct methods.