client decoding will help avoid transcoding at the server end, which no doubt is great and many people will find useful and be happy about, but in the end, it is not the same as direct pass-through, and more importantly prevents transmission of atmos/dts spatial metadata.
For TrueHD, Direct Stream of the video and Transcoding of TrueHD to FLAC is the best you are going to get. You may not prefer this method that Plex has chosen but the result is the same because quality wise it is still lossless.