Well, both HoT and PoF final fights weren't turned in a strike so it doesn't really mean much.
Also where did they say they the strikes will be part of the story of the first 2 maps?
Of course it can't spoil anything from the third map, but it could also be a rift enemy, for example. Or a meta boss like the boneskinner
Especially for the first map, we could have no big boss at all during the story