well because those people are not representing themselves as the real deal, they are merely 'acting out' in a manner similar to that of the actual star/celebrity/person. the fact that i mentioned the section was to stress the fact that the police is likely to construe this act as that of personation, and act accordingly.
on a different note, let me give you a section from PPC that is actually not being implemented:
294-B. Offering of prize in connection with trade, etc.:
Whoever offers, or undertakes to offer, in connection with any trade or business or sale of any commodity, any prize, reward or other similar consideration, by whatever name called, whether in money or kind, against any coupon, ticket, number or figure, or by any other device, as an inducement or encouragement to trade or business or to the buying of any commodity, or for the purpose of advertisement or popularising any commodity, and whoever publishes any such offer, shall be punishable, with imprisonment of either description for a term which may extend to six months, or with fine, or with both.
meaning that any or all companies/persons advertising and/or offering prizes, contests, gifts etc. or any other thing or offer of similar nature, that encourages the consumer to buy their product, are in violation of this section of the Pakistan Penal Code 1860 and become liable to be arrested and prosecuted. now, turn on your TV and see how many such offers and contest are taking place on a routinely basis even pakwheels is doing it with their 'car awards 2014 survey', offering an ipod touch as a prize