Is HEMA suitable for law enforcement and other security services?

Yes, very much so. Professional security personnel often has to head towards the violence instead of creating distance from it like any sane citizen ought to do. 

The Historical European Martial Arts are millennia old, developed over time while being used in actual combat in a wide variety of situations.

As there are many different kinds of violence and volatile or even violent situations the martial art used needs to be flexible. After all, giving a crazy old lady a low kick just because she is throwing cans around in a supermarket isn't very professional. HEMA by its nature is very scalable and flexible, thus fits this base requirement perfectly.

The hard part is finding a teacher that can teach you all the other meta-skills that you need to apply a martial art in the real world violent situation, that however is a problem all martial arts share.