Interestingly, I actually agree to both sides.
On one hand, it definitely is to be strictly avoided to link your RL identity to any online pseudonym. It's OK for people you trust, but in general, just asking for trouble. By now, the governments aren't the ones spying on people most excessively. Corporations are, having have various reasons to do so, ranging from judging prospect employees over spam right to identity theft. Add to this that in any given country, there is only one government targetting you, while there are lots of corporations.
On the other hand, the act of making it appear as if someone said something that they did not say, even if you think that you can accurately deduce the "actual meaning", borders on lying (especially when, like in a heated discussion, the things that one reads may differ greatly from the things that were written). Therefore, this practice should not be employed, nor should it be allowed. Whtether or not it can actually be verified or prevented is sort of irrelevant; what is relelvant is the message that is sent, which is either "feel free" or "don't do that". I actually think that, if the intent truly is to represent some form of "I'm a psychic and know what you think" style stuff, it would make for a very poor effect. The crucial differences, which make up the point, may easily get missed, even if blatant, due to all sorts of circumstances.
The only thing for which this could be used to great effect is, as has been said, for producing false evidence, which is something that shouldn't be allowed in any decent forum, anyway, and naturally won't be employed by people who try to be decent forum members.
Therefore, while it shouldn't harm you outside the forum in question, it's bad, and inefficient, discussion practice.
