It is May 5th everywhere in the world – but ONLY in Mexico is it a legal national holiday. In the USA – today is May 5th, not “Cinco-de-Mayo”. Cinco de Mayo is the Mexican holiday of their national Independence – our national holiday of independence is July 4th.
Anyone in the USA who would choose to celebrate today, but if given the chance would spit or walk on the US flag (or it’s military or the veterans who have served it) should not consider themselves welcome within the US. If you want to celebrate “Cinco-de-Mayo” – go to Mexico.