I'd venture and say 3.5. There is just too much mass for that to be a 2.5 year old in my opinion. Most 1.5 year deer that I see score in the 50-75 pt range. To see a deer grow an additional 60-70 inches in the second year is a stretch when it is known that the majority of nutrients the buck intakes will go towards core body development. Once the third year comes around, then you can start seeing greater antler growth.
Now that is not saying that a freak 2.5 year old can't grow some massive "horns". But I tend to talking in general probability and greater likelyhood of something being true. Kinda like why I don't hunt my backyard. I live in a subdivision and I got tracks in my backyard, but have never seen a deer there. Sure I COULD kill a deer back there, just like that deer COULD be 2.5 years old, but I am placing my hunting odds somewhere other then my backyard, just like I am placing my best guess that he is 3.5.