Are you sure that it was the Sea Ceptor you were reading about? The follow-on to the CAMM which is the base for Sea Ceptor is the CAMM-ER which is in development. Some of the preliminary results I have seen indicate a range of ~50+ km, or comparable to that of the ESSM.
For low flying targets, one of the primary issues is going to be the limited radar horizon. Having said that, having the option to cue and launch missiles at a target further away detected by other assets has advantages. A limitation of a system like Sea Ceptor is that if the frigate is acting as an escort, other vessels need to remain within that 25 km range to stay within a Sea Ceptor defensive "umbrella". That likely is not much of an issue if just one or two other vessels are being escorted, but could start to become problematic if a frigate tries to provide an escort to several ships at once.