Per the article:
On Instagram White wrote: “Don’t even think about using my music you fascists. Law suit coming from my lawyers about this (to add to your 5 thousand others.) Have a great day at work today Margo Martin.’
It looks like “threatens a lawsuit” is being used here because “sues” would be inaccurate (since the suit has not been filed).
Hate to break it to ya boss but part of speech is descriptive, not prescriptive. Childish would be insisting that every word stay in the tidy little box assigned to it rather than recognizing and appreciating language’s flexibility and constant evolution.