AFAIK any modification to LGPLv3 code must be distributed under LGPLv3.
The difference with GPL is that you can include or link an unmodified LGPL work into a proprietary software and distribute the whole with a different license.
But if you modify the LGPL work itself and redistribute it (in binary or source form) you must use the LGPL license as it would obviously be a derivative work.
Even wikipedia confirms this https://en.m.wikipedia.org/wiki/GNU_Lesser_General_Public_License#Differences_from_the_GPL
Thus you should clarify the related paragraphs: using LGPL for the distribution of derivative works is not a suggestion but a requirement of the license.
Also, when I talked with a lawyer about a derivative work of a BSD software he explained me that I could distribute my modified version under AGPLv3 because I had introduced and modified several parts and my modification was under GPLv3 so the work as a whole was GPLv3, BUT I could not alter the copyright statements in the files I was copying verbatim from the original BSD project.
So my suggestion is to talk with a lawyer specialized in sofyware copyright about Redict before distributing Redis code under a different license.