Wow, sorry to hear the teacher's reception of this information was horrible. Nothing like someone saying 'Aha!! got you!' as you offer them some very sensitive information.
I have definitely been in the over-protective, not so "smooth" mode a time or two, in fact still feeling a bit silly for over-reacting the other day to being told ds isn't currently eligible for some more testing. (long story).
Well we have 2e with our ds10, but the second e is subtle and he can do well enough that there are no accommodations deemed necessary by the schools (that might be what the 'good luck' was all about). Our Dr. did warn that eventually accommodations might be deemed necessary as our ds' work dips below the usual A's....way below. I have yet to see this happen, but he said middle school is usually the time frame he would expect impact to begin to show. But that doesn't mean right now he isn't frustrated and sometimes discouraged.
Not sure what 'relief' class is, is that supposed to be for gifted/advanced kids?
Have you taken this to the principal/school counselor/regular teacher yet? Hopefully a group of folks will be able to come up with a more respectable response. I do hope you have good luck, but I mean that in a good way.
You've taken a VERY important step in finding out what is going on with your ds, you are doing a good job!!