Jelquing have been a controversial excersize per se in the natural PE community, because some people have reported vascular damage from practicing it.
Furthermore , it would take many months of dedication to see small gains with Jelquing, much smaller than what filler gave you.
I think it comes down to the safety of Jelqing in general. I don't believe the "Jelqing of the PMMA enhanced penis" is going to upset any results post-6 weeks, but whether it can have an adverse affect on the penis overall is hard to ascertain.
I say this because I sometimes wonder if it's men performing jelqs incorrectly (i.e. too aggressively, little downtime, etc) that lead to injuries; but then again, some men are already predisposed to these types of injuries, and no amount of "correct technique" could have foresaw injury.
I've done (wet) Jelqing pre-PMMA over a decade ago with some success in length gains but largely attribute that to improved EQ (Erection quality). I haven't really tried it much post-PMMA, but it's not unheard of.