(To Amateur Obsessive, though all are welcome)
Hello, and thanks very much for the welcome. I admit I am relatively new to Wikia, and I do get a bit (well, a lot) carried away when it comes to Moriarty. I want to apologize if I came off as rude at all, because I certainly don't want to make any enemies in a new community, just the opposite.
So, back on the subject, I'll start off by listing a couple of reasons why I believe Moriarty should be referred to in the present tense:
1. At the end of HLV (no, I mean the very end), we see without a doubt Moriarty alive and breathing, which seems to clear up any confusion after the uncertain gif-like video on the screens of England. We can never know for sure, obviously (until series 4 airs), but it seems logical that in light of what we know to keep him in the present tense.
2. People who are new to the show/who haven't seen TRF yet may see him being referred to in the past-tense and be confused, so therefore keeping him in present tense would save spoilers and confusion, because they wouldn't be aware of series 3 anyway, besides the reason I gave above.
Also, I noticed that on CAM's article, he has a date of death. Moriarty's doesn't, though you are insisting on keeping him in the past tense. Since his fate is unclear enough to not include a date of death, then perhaps it would also make sense to refer to him as "is".