As Ngatimozart has already replied the USCG HC-130 certainly isn't a player in the FASC project, however it is of interest nevertheless! The FAMC project includes a requirement that the platform chosen is capable of SAR tasking - and in that capacity it would be deployed more or less in the same manner as the HC-130.
Use of a FAMC platform in this way will relieve the FASC of some of these taskings and is no doubt a factor, no doubt influenced by cost, in the decision to go for no more than 4 FASC airframes.
I still think 5 FASC airframes would give better lifetime availability & allow more operational flexibility but I suspect that 40 sqn is likely to pick-up more of the more 'basic' SAR taskings, with a little help from 42 sqn, whilst 5 sqn looks to play with real toys in a much more exclusive sandpit.
p.s. I should add that the HC-130 obviously is better equipped than your average heavy lifter with FLIR & Search radar etc etc, so yes 5 sqn will still get plenty of SAR work. 42 sqn it seems will be able to do more of the 'closer in' SAR and it seems will get systems to allow it to do so.