In the practical world, regarding AGM's and "inrush current level", there is probably nothing to worry about. To attain an inrush of current with a high DC voltage, enough to damage a battery, you would need some serious power supply and huge transformers. I believe they may be using the term "in rush level" to define the initial charge rate rather than the standard electronic meaning.
FWIW, I dabble with inrush current in some of the amplifiers I build. It is a matter of taming the AC inrush current so that a transformer or components immediately downstream are not damaged or their lifetime reduced. The current is limited by a soft-start circuit or the use of thermistors.