ENTP vs INTP...
If an INTP is cheerful when you observe him is he not more animated, more talkative and more interested in life in general? Does his type change to ENTP to incorperate this new more extroverted approach? (I know it's not a perfect extroversion-introversion definition but stay with me here)
Of course not. Even if an INTP were to start having large parties and craving people's attention he would still evaluate information before assimilating it into his thinking. He'd still be an avid observer and likely to focus too much and analyse past the point at which most people stop.
The type is about cognitive processes, not behaviour, flaws or anything else derived from it. These things can be indicative of a particular type or preference but they are almost without exception never a direct link.
A imples B does not imply that B implies A.
INTP 4 Eva. The "opposition" fails.