Sparlock is forever immortalized on the DVD, so he can't be axed any more than he has been already via the blue dumpster. I doubt he'll be making a return in any of the forthcoming Caleb sequels anyway.
Indeed. The 'Sparlock' character was almost certainly only ever intended as a once-off plot device in a particular episode of the 'Caleb must Obey' series. Though the character is significant in certain contexts (e.g. forums such as this), the character is not particularly notable within the scope of the series narrative, so there would be very little reason for them to continue using the character in future 'lessons' even if there had been no negative reaction to it. In any case, the JW leadership thrives on negative publicity because it feeds the JW persecution complex.