No. 'Quote mining', as you call it isn't just acceptable, but conditionally proper. It's considered tacky and in bad for to quote entire blocks of irrelevant text. This is especially so if it's the immediatly preceding post.
I haven't looked at the particular post you're accusing him of doing this, but you've accused me of it in the past. As long as the quoted material does not change the context there is no issue. I've challenged to you to demonstrate a violation on this conextual rule when you accused me of it and you didn't respond. If the quote is kept in the proper context it's not only accpetable, but proper. This has been a standard on the internet for quote a long time, probably about the same time when it was agreed that all caps was shouting. If you have problems with someone quoting something you said that puts you in a bad light, identify the correct context (thus validating your original statement and discrediting the quoter) or don't say stupid things. Complaining about people not quoting your entire comment, speech, or diatribe, is tacky, obnoxious, or a desperate attempt to deflect attention from something that you did in fact say.
Here's a free internet lesson for you on etiquite. If you say "I like boys soccer. I think it's an excellent sport, and it makes my son a better person by playing." it's perfectly find for someone to quote you as "Tim, you said that you "think it's an excellent sport."" when speaking aboutboys soccer. It's NOT, however, OK to quote you as saying "I like boys". While you did say that it's wholely inaccurate as it completly removes the context. THAT would be a legitimate gripe.
