Formation with Ob Sec (troops?)

The Blood Angel codex has the Battle Company Formation that states under the special rule Objective Secured that "ALL TROOPS units selected from the formation gain Objective Secured special rule (see page 122)". The same wording is on the White Dwarf Angel's Fury Spearhead Force.

The Dark Angel Battle Demi-company and the Space Marine Codex one have a slightly different wording for the Objective Secured special rule. "A unit with this special rule controls Objective Markers even if an enemy scoring unit is within range of the Objective Marker, unless the enemy unit also has this special rule."

These newer formations still only have objective secured on Troops and only Troops, right?

That would be how I read it. Each codex is seperate from the other, rules wise. Where one codex may grant an ability to numerous units, another may only grant it to some, and another, to none at all. If the Blood Angels codex says Troops only, then that's all that get's it. You might want to check the errata to see if it was updated though.

I'm wondering if Devastators or Assault Marines in the Space Marine and Dark Angel Demi companies get objective secured.

It's a rule that applies to the formation, so all units in the formation have it