It makes perfect sense.
With the increase in temperature required for lead free solder, and the lower resistance of lead free solder to oxidation having an oxygen reduced environment is likely to significantly reduce joint/solder/tip damage due to oxides.
Same as back-purging when TIG welding, or puring with inert gas when brazing copper. I keep a cylinder of Nitrogen around for both (nitrogen is cheaper than Argon for purging, leaving more Argon for welding). If I had a lead on a cost effective N2 generator I'd swap out my Nitrogen bottle in a heartbeat. I'd imagine for continuous use like soldering, the only cost effective method is a generator.