She became a resident of the USA in 2001 and a citizen of the USA in 2006, hence a citizen for about 10 years.
The issue with Trump is illegal migration instead of applying legally. This is reasonable and is how governments view migration.
Europeans will also have to go through a citizenship process no matter who is in power
She worked here for 7 weeks before being granted a work visa, that made her an illegal immigrant for 7 weeks. Also, in order to get that work visa, she would have had to have lied about her worker status, meaning that she obtained the work visa under false pretenses, making it null and void. Any amount of time she worked under her fraudulent work visa was also time spent as an illegal immigrant. She did not leave the US, and go to the back of the line before becoming a legal resident in 2001, so her becoming a legal resident was also fraudulent. She got married to a US citizen in 2005, so her becoming a US citizen in 2006 was above board, but she lived here as an illegal immigrant for nearly 10 years before becoming a citizen for the last 10 years. Trump, and many of his supporters, do not want a pathway to citizenship for illegal immigrants unless they leave the country and go to the back of the line, this makes them hypocritical when it comes to not caring about Melania's illegal status for 10 years. Unless they only care about that when it comes to Hispanics, which would make them racist. I suppose we can let each of those people choose whether they fall into the hypocritical camp, or the racist one.