Apparently, it is not necessary to be a member of the House of Representatives to become Speaker, it is only necessary that a majority of the House members settle on one candidate.
Technically, the Speaker of the House only holds that position at the sufferance of the majority of the members, and may be voted out at any time there is a crisis of confidence.
Well, it takes a lot to get to the point of voting someone out. Look at Boehner? He needed to go for years. Better to start things off right and not say ‘we can wait and do something about it later if there’s a problem’. No one in DC has the guts to upset the apple cart.
The usual gang of suspects (big business stooges) are trying to eliminate the rule allowing a vote of no confidence to force the Speaker out in mid-term. There is about to be a quite mischievous lame duck caucus of “Republican” members of the 2014 to 2016 Congress to eliminate that rule and to nominate Paul Eunoch Ryan to be Speaker for 1/2017-1/2019. The actual election of the Speaker will be formally done by the 435 members of the NEW Congress but the nominees are determined this year by outgoing Congress members.