I agree with you, but still the OP was complaining basically about how he wasn't fully geared within 3 hours of hitting 85 as a tank and so I can see the reply being a bit "condecending". Yes a better answer would have been explaining about rep items, regular instance gear, possibly some gear from Twilight Highlands, and if they still want to rush into heroics under geared to rush in as dps and not tank, sure they won't be able to politely roll need on tank gear if they que as dps but they could start stocking up on JP to buy tanking gear.
Point being yes his reply was harse and uncalled for but some people get more easily upset then others when they hear people complain about how "It is not fair that the doctor who spent 15 extra years in school and worked his/her ass off to learn the trade and do the job makes more money then me when all I have done is work as a cashier at McDonalds for 2 years and have been sitting on my ass the past 2 years collecting unemployment because I got caught buying coke at work. Even though I have done nothing to deserve money I should get just as much per week as the doctor because its not fair that he/she has what I don't" bull that socialist like to complain about. I mean that is over exaggeration for the point the OP and replier where making but to get a point across clearly it is easiest to over exaggerate.