Not completely true. It depends on what (pre)installation was perfomermed and by whom.

Below is a list of the perl that got installed at installation time as system's perl. As I always use my own compiled versions, I do not care to update the preinstalled version, so I may say I think it was installed as such by default:

For modern releases, HP has an official depot available for free here. Next to that, the HP Porting Center has recent versions of perl available on a restricted number of OS releases here. I have almost every version of perl available for all of the above HP-UX versions here.