That's not quite true, you have to spend 5 points in previous tiers to unlock the next, so: -
You have to spend 5 points in tier one to unlock tier 2 then,
you have to spend 5 points in tier 1 & 2 to unlock tier 3, then
you have to spend 5 points in tier 1, 2 & 3 to unlock tier 4 etc etc,
This way you can easily build a PvE spec without including any PvP related talents.
The slow referred to in the PvP related abilities is a movement slow and nothing more, this is incredibly useful in a PvP situation but really not all that useful in a PvE situation. Even less useful in a Flashpoint or Operations group, so the abilities that provide it are generally avoided in an end game PvE build.