Looks like there are two questions here.
1) a See Also is not a source, but relevant info. It could be a lot of items, such as a county history book that doesn't have source citations (which should be tracked down and verified if there are some). Great for clues, though.
2) Find-a-Grave without a photo. Is there anything else on that profile page? Where did the person who set it up get their info? If there's no marker, I'd lean toward No, not yet. Anyone can set up a memorial and type anything into it. The photo makes a difference. Are there any cemetery records, newspaper items, birth or christening records, family Bibles? It depends on the place and time what might be waiting to be found. I'd be leaning toward leaving it as a See Also, with Research Notes about what records have been sought, and what else might be sought.