I don't think so. Wheeler & Rosenthal in their "Saint Nicolas: A Closer Look at Christmas" give some details about the historicity of St Nicolas in their first chapter.
Many of the acts attributed to Nicolas are probably embellished, but not all.
The 151st attendee listed in an AD 510 manuscript of attendees of the Council of Niceae was "Nicolas of Myra of Lycia."
A neat link: A Nicolas Timeline
185 years later. How about a more contemporary reference that he even existed? I'd expect someone would have mentioned the Man Who Punched Out Arius.
Or the Church at Myra was enmbarssed they didn't have a Bishop at the time of Nicea and invented one.
"When the legend becomes fact, print the legend."