If you've read AvX 5, then you know about the 5 X-Men carrying the Phoenix with them after whatever happened when Ironman hit it. None of them would be able to host the entire PF, but apparently all of them are powerful enough to carry a part of it (the Cuckoos were able to carry it in parts after all).
One of them is Scott Summers.
During Phoenix Endsong, it was revealed that the PF wanted Jean to be with him because the energy from his optic blasts could feed the Phoenix forever.
Now Cyclops himself is hosting a portion of the Phoenix Force. Being a living battery that can keep feeding the Phoenix, would even just a fraction of it be completly invincible? No matter how much power it uses, it will never weaken because it has access to unlimited energy to keep gaining strength. In a sustained fight, would it even win against old hosts of the complete phoenix force?
I know we don't have any feedback of how strong are this new hosts (except for Cyclops getting rid of the avengers, including red hulk, with a single shot before leaving to earth), but it's still a power based on the Phoenix with access to Cyclops energy which feeds it.
PS: There is still the possibility that the writters completly forgets about this and PIS any battle involving him ¬¬