This struck me as an odd comment. Because the iOS tablet market is non-existent outside of the iPad lineup.
Developers making tablet apps will most likely see more profits from their iPad versions than their Windows tablet versions, so iOS takes priority due to the sheer number of users in the market, not variety of devices in market. And so on.
If one does a search&replace: s/Windows/WindowsRT/ :
"Obviously Windows RT has a similar implementation, but the unfortunate truth is that the Windows RT tablet market is almost non-existent at this point outside of the Surface lineup."
(I would appreciate if the downvoter who thought my interpretation was incorrect to reply with the correct way to read the author's sentence. It seems that Brandon Chester is quite aware of the difference between Windows RT vs Windows tablets : http://www.anandtech.com/show/8736/best-tablets-holiday-2014...)
There are plenty of Windows tablets at all sorts of price points, but most seem to be using x86 instead of ARM.
The author didn't mention "Windows 10" specifically but instead, just "Windows" which can include the previous incarnations (both Windows 8 & Windows RT 8). The non-premium Windows RT had "multitasking" several years ago when iOS did not and that was the particular point of comparison to trigger his hard-to-parse statement. He also qualified his sentence with "outside of the Surface lineup" which seems like he was aware that Surface has turned into a somewhat of a success story for Microsoft.
http://www.zdnet.com/article/microsoft-surface-hits-1bn-reve...
http://www.engadget.com/2015/04/23/microsoft-q3-2015-earning...