According to E! Online’s Kristin:

What happend to Ryan (Luke Grimes) on Brothers & Sisters? He is a regular but only appeared in 5 out of 15 episodes so far…
According to sources, he is being “phased out.” I’m told “he didn’t really fit with the cast from the very beginning.” Maybe Rob Lowe can get him a new gig wherever he ends up?

• • Name: Pats
  • Date: February 23rd, 2010

  WHAT?!
  “He didn’t really fit with the cast”!?!? Sure.
  His character was so underrated on the show
  But it’s not Luke’s fault if the writers didn’t know how to recognize a great (and sexy) actor with a HUGE talent like him. (He’s the next Johnny Depp, people!)
  This sucks

  We love you, Luke!

• • Name: Steph
  • Date: February 23rd, 2010

  Wow, that really sucks! Luke has been way underused on the show, they had heaps of potential with his character even, but haven’t really taken it anywhere. Poor Luke =(

• • Name: Jason
  • Date: March 23rd, 2010

  You’ve got to be kidding me! They made such a huge deal about who the extra brother / sister is for like a season or two and now that they’ve made the big reveal, they’re going to “phase him out”. Then what was the point of even bringing the character of Ryan into the story line in the first place! Luke is HOT and they’re making a BIG mistake in letting him go. I’ve stopped watching the show on the main part because he wasn’t in many of the episodes.