How does owning more land lower taxes? Since it is for conservation, it may be taxed at a low or zero rate (since if it can't be farmed or developed it doesn't have much value) but no land has property tax credits.
The purchase price will be an expense for income tax purposes but they actually spent the money. They will only save some percentage of the purchase price. This effectively reduces the purchase price but doesn't save them overall.
The most interesting thing in this story is that land near WDW costs $230,000 an acre in bulk undeveloped. No wonder anything residential I've seen along I-4 is high density stuff. If you even developed 1/2 acre lots, after the roads and green space/common areas it will be close to $150,000 just for the land. A 2000 square foot home is going to cost over $200k in construction cost. Plus you have to grade the land and put in utilities and infrastructure. For a developer to get any kind of ROI, that home would have to be sold for over $500k.