It seems most likely to be a terrible idea. I didn't follow any of the above links, but did look into the subject once, mostly out of idle curiosity, and found some older threads on the subject right here in FreeBSD forums. I'm not going to revisit all that again now, and I didn't take any notes at the time, but my admittedly rather peripheral understanding is that the Widevine people want something like peer status with the FreeBSD operating system, because their priority is digital rights (i.e., copyright enforcement), whereas FreeBSD priorities really are not.
And some of the decision-makers for FreeBSD, if I'm not mistaken, had the feeling that this would be too much of a security compromise for an operating system whose primary mission is "the power to serve."
I admit to sometimes using FreeBSD as a multimedia system and as a desktop system. I first installed KDE on FreeBSD way back in the 1990s, when it was necessary for me to install FreeBSD using CDs. Maybe it was 2001 or 2002, I'm not really sure. The internet was still a bit of a baby way back then. KDE actually did work on it, believe it or not. You could go on the internet with it, and it was a lot of fun. (Netscape browser? I can't really remember for sure.) And, if I went to certain ad-heavy sites, popup windows would propagate so quickly that sometimes, unless I was quick and really on my toes, I couldn't shut the system down without using the power switch. It would start thrashing and basically lock up the whole system. I'd never install anything like that on an actual working server however.
Likewise, I'd never install Widevine on a server, even if it was possible, which apparently, it isn't, not on FreeBSD, and not unless you put Widevine in some kind of Linux jail, or use some other kind of workaround trick like that.
Sometimes I do mix desktop environments with server systems, but I only do this on development machines, and that's primarily only done so that I can use the same laptop both as a web server host and as a web browser host for testing purposes. I don't think that working live server systems really need a graphical front-end, that's just window-dressing.
In short, if I wanted to use Widevine to watch Netflix, I'd use some kind of Linux system, or a commercial system like MacOS or even (shudder) Windows. I wouldn't try to force FreeBSD to be something it's not. I know others feel differently about it, but that's my take. I don't want to see FreeBSD compromise "the power to serve" in order to accommodate desktop environments or multi-media entertainment systems. It's not worth the compromises.
