"You know what I love about this country?
Its amazingly short memory.
We're a nation of amnesiacs. We forget everything:
Where we came from, what we did to get here.
History is last week's People magazine."
When TV characters talk about People magazine in Toobworld, they are not referring to the publication to be found in the real world. It's to the magazine from Howard Publications that could be found in 'The Name Of The Game'. Its publication was overseen by Glenn Howard and Jeff Dillon was one of its main writers.
As we can see, using that premise, Howard Publications was still publishing People in 1991 and with every mention of the magazine since then in dialogue from many TV shows, both dramas and sitcoms, it will always be considered the fictional magazine found on Earth Prime-Time.