So based on a few vague comments, I managed to track down what the issue is since neither this nor the previous/. article nor the sites opposed to it (who seem to want to portray it as a Big Evil Government conspiracy to take away your freedom) delve into it. 

Several airports use Terminal Doppler Weather Radar [wikipedia.org] for high-resolution maps of storms, rainfall, and most importantly (for airports) microbursts[wikipedia.org]. TDWR operates at frequencies from 5.60 - 5.64 GHz. That's smack dab in the middle of the 5 GHz band used by 802.11a, n, and ac[wikipedia.org]. You'll notice use of those specific frequencies (channels 120, 124, 128) are prohibited in the U.S. and Canada for this reason. 

Based on that, it sounds like the issue is that you can buy a 5 GHz device off the shelf, then hack the firmware to re-enable those frequencies. And the FCC is proposing this action because people have been doing exactly that and the FCC has received reports from the airports of such interference on those frequencies. 

-- 
David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
davecb@spamcop.net           |                      -- Mark Twain