Sometimes cheaper = "better".
If you're looking for TOS for CAS/SCAR, then yes the UAV would be better. It's why the MQ-9 guys are running the SCAR show in parts of the world now- you don't need to do a hand off every 20-30 minutes, and it frees up the manned assets to check in, clean their wings and check out. If they have a target that needs killing and no strikers to do it, they can do it themselves.
The F-35 has/will have some pretty sweet capabilities, but so do/will UAVs. FWIW, in the Air Force, UAVs/RPAs are dropping more ordnance than all of the manned assets put together. That's a shit ton. The Syracuse ANG unit is busier than most any regular manned fleet unit. They have been deployed for over 6 years now, and are executing missions daily around the world. Meanwhile the manned units are rotating in and out, and doing UDP style stuff. IF the manned guys are better, why are UAVs doing so much more than the manned squadrons?
We're not saying that UAV's will do air to air stuff (yet), or than the F-35 is useless. But when you can buy 2-3 squadrons of MQ-9 for what one F-35 costs- why the F would we being doing MQ-9 stuff with an F-35?