But does this still tag them as having a person in the photo if I did a search for photos with people?
Clicking "Ignore this Face" for a group of photos will remove the suggested face from the strip of unnamed faces below the faces album. But it will not remove the faces circle from the photos, if you have "View > Show Faces Names" enabled".
For example, in this library I rejected all suggested faces, but some photos are still showing unnamed faces, when I enlarge the photos. I have to click the "x" to remove the faces thumbnail as well.

But still, it is better to "Ignore" the faces than to add them all to a special faces album "Strangers", because that would influence the faces recognition algorithm. Ignoring a face tells Photos that it is a face, but you do not want it to be recognized.
I ignore the faces strip completely and name the faces by browsing the faces enlarged. If a face is marked, that I don't care for, I click the "x", if a face is marked that I want to keep, I type a name into the name field. The advantage is, that I am seeing the faces in the context of the full photo this way - and I know when and where the photo has been taken. It is much easier to remember the names of people, if I start from a certain moment.