The word strikes me as being regional jargon; an idiomatic expression that, prior to today, would not have passed muster in a game of Scrabble.
To come to terms with its usage, you have to identify the various definitions of "funeral" and then decide which one fits and whether or not it can be reasonably 'ized.'
To 'ize' something is to cause it to be more like something else, both literally and figuratively. In some cases, the end result is meant to be more exact, e.g., to crystallize a point would mean to give it more clarity, whereas, to crystallize a liquid would mean to turn it into actual crystals.
In my mind, a funeral is an event; a multi-faceted ceremony, meant to eulogize and finalize one's death. With this definition, you could "funeralize" a non-funeral event but not a person. That said, I can better understand the etymology of the term if I dig a little deeper into the definition of "funeral"...
To "funeralize" a person, you would have to define "funeral" as the sum of its parts. As such, the physical act of "laying a person to rest," through burial in the ground or scattering of ashes, is where the funeral becomes the person and can therefore be 'ized,' as it were.
I believe the word, "funeralize," was intentionally spoken in the situational vernacular, as a show of solidarity and respect for the family of Sgt. La David Johnson; in light of the social polarization of recent, unsavory events.
Thank you, CTyankee, for your thread and for making "funeralize" the word of the day.
TYY
Disclaimer: All of this is just me trying to rationalize "funeralize" and is not meant as a treatise on the subject; hence, the freewheeling hybrid quotes.