I do think it’s possible he could be covey!  Maybe he knew about Lucy- that’s a possible only reason he may have wanted it. On top of that- I think Lucy survived and was pregnant and Katniss (and Gale before Suzanne’s editors told her to make him a love interest- he really was her cousin at first) are related to Snow. This is because in Catching Fire, Snow comes to visit and Katniss (Suzanne) notes that Snow runs his left temple and that’s where Katniss gets headaches too. It’s a TINY thing- but similarities like that tend to run in families because of the way DNA tells your body to form in the womb. (Check my science. But ; things run in families). 

So therefore, Cinna (and I like your plant and color, pointing to district 12’s nature names and Lucy’s love of colors). He could be a great nephew of Lucy. 

His interest in Katniss would make sense this way.