This is trivial...it doesn't matter the miner itself. You can mine under windows but proxy server may be linux/bsd/mac etc. ..the rest is the same as your post.
Agreed with you. Actually, the miner contains some countermeasures against this kind of attack. But anyway, it does not matter what OS someone uses, if one wants to cut the fee, he will do that.
There are no countermeasures when proxy is really transparent ( not /etc/hosts record)..
Claymore's auditory is windows home users with 1-6 cards, they will not bother about crappy 2%, but if you have 1000+ cards, 2%=20 cards, more then 3 full rigs, and you start thinking about it.
And for all: claymore=bad, but many people don't understand it, they press F5, waiting new version, but total net hashrate grows up, and profit from a card becomes lower, because of higher and higher wattage.
So large farmers hate Claymore, and he knows it, and they will do all to cut off fee and disassemble his miner.