It says "progression" for bent-knee push-ups (and for some other exercises). It's a way of going from zero-to-hero, rather than not doing them just because they are too hard.
I must say "army_paralegal", based on posts that you have made in any number of threads, that you have an aversion to doing pushups, at the least, to doing PT, at the worst. If the prospect of doing PT strikes fear into your heart, do everybody a favour, and don't join. We have enough people in the CF who don't want to be physically fit as it is, and we don't need any more. Watch the CF from afar, but don't join out of some romantic notion.
If it is too hard to do in it's "full" form, do the progressive style outlined in the link you gave. Work on technique and form, not numbers. Don't expect to go from doing half a pushup to 100 one-armed pushups in a week. It'll take time. And if you think that it's too hard, well, there's not much point in joining, because frankly WE don't want you, because if you want to cop out because of a few measly push-ups, what will you do under real pressure??? Quit?? Thanks, but no thanks.
Al