Cuck is an all-encompassing term
AKA "means everything and nothing". So, as a consequence, the same could be applied to the whole retarded "cuck licence" meme.
a programmer who allows themselves to be exploited
How does one get exploited if he/she voluntarily releases program under a lax licence? By the way, BSD licences other than the 4-clause one are GPL compatible, so FSF cultists can still use the code. Less licence restrictions means less potential problems to further adopters or redistributors. I have seen enough pointless shitshows, as well as sabotaging, revolving around GPL terms.
enables users to become useds by permitting other developers to build proprietary spyware on top of their own software
This is starting to give some schizo vibes. The original code, even if used in malicious way by some adopter, does not automatically disappear. While it is indeed a shit practice for huge and rich companies to leech off volunteers and give nothing back, your generalisation went way too far. It's also not like you can not do something similar with code under any other licence - it just boils down on how well you are going to obfuscate it. Licence does not magically do/cause anything on its own anyway. This whole unhealthy obsession over le licences seems to be a very USA thing and, due to its influence, has unfortunately spread worldwide.
current usage(s) of the word
In other words, misuse by knuckleheads who are too retarded to check the meaning of a word they want to use in a dictionary. Sorry, but I remember well how it got popular: 2014 was the year classic 4chan got formally murdered, through events like closing of World4ch, introducing WebM, moot going for a love quest, GaymerGate, moot purging long-time moderators and janitors because he felt 4chan interfered with his love quest, fappening and introduction of DMCA policy. All that brought an influx of newfags unwilling to adapt, who instead used the chaos to introduce their reign of cancer. One of many symptoms was the word "cuck" which they pushed hard to replace "faggot" for no reason. It was retarded then and is just as retarded now.