[Political Junkie Too]

Because the 22nd amendment is the Presidential term limit of two terms or 10 years, and Obama hadn't reached the limit yet.

-PJ

[WildHighlander57]

I meant why didn’t they (other candidates) challenge this part, an ineligible person running?

From your post:
“.... A person who is ineligible to serve cannot run for office. Running is the act, and the other candidates have standing because they are harmed by an ineligible candidate that is running nonetheless. ....”

Any of the candidates (p&f, green, aip, constitution, etc) could have challenged, not just the top two parties (r&d).