There is one other issue, although I'm not 100% positive how it works. But AHL playoff rosters, or at least players who can be eligible had to be submitted to the league (AHL) some time ago. If a player is not on that list, then they are not eligible to play in the AHL playoffs.
There may be loopholes or exceptions, I'm really not sure, or Karlsson's name may have been included. But I will try to find exactly what the rule on that is.
OK... here is the break down... found here AHL CLEAR DAY
"The American Hockey League has released the 2008-09 Clear Day Period lists for each of its 29 member clubs.
Each Clear Day roster consists of a maximum of 22 players.
According to AHL by-laws, only those players listed on a team’s Clear Day roster are eligible
to compete in the remainder of the 2008-09 AHL regular season and in the 2009 Calder Cup Playoffs,
unless emergency conditions arise as a result of recall, injury or suspension.
Teams may also add signed junior players or players on amateur tryout
contracts, only after their respective junior or college seasons are
Basically, other than on an emergency basis the only other players that can be added to AHL play-off rosters are those signed from their Junior or College teams. Since the SEL is technically a pro league I don't think Karlsson would be eligible.
Some names to note that were either included or excluded from the B-Sens list.
Elliot was excluded from that list, so it'll be the Jeff Glass show. Also not included was Ryan Shannon. Of names we saw at least semi-regularily in Ottawa, Bell and Lee are included and thus eligible to play. as are Regin and Zubov.