Plaid & SNP to be excluded from Welsh & Scottish Affairs Committees?

During the Business of the House debate in the Commons yesterday Elfyn Llwyd raised the following point of order:

Elfyn Llwyd (Dwyfor Meirionnydd, Plaid Cymru)

On a point of order, Mr. Deputy Speaker. We are in a position today where we are discussing motions that will effectively exclude Plaid Cymru Members from being a member of the Welsh Affairs Select Committee and Scottish National party Members from being on the Scottish Affairs Select Committee. Additionally, there will be no room for those parties' Back-Bench Members to sit on the Back-Bench business committee. What kind of motions are these? What is the point behind them? I urge the Minister to take them away and think them through, as these motions will not stand the test of time, and the people in Wales and Scotland will be furious when they find out.

However his point was ruled out of order by Deputy Speaker Nigel Evans.

Mr Llwyd attempted to raise the same issue during the progress of the debate, but was again ruled out of order by Nigel Evans.

Given that Plaid is a party of Government in the Assembly and that the Committee has a huge responsibility for scrutinising Assembly eLCOs, it would be strange and undemocratic if Plaid was excluded from the Welsh Affairs Committee. Because the matter was ruled out of order by Mr Evans, I don't know what the background to Elfyn's complaint is. Can anybody shed any light on what is happening?

UPDATE:
Whilst I was posting this Adam Higget posted the background to the issue on a site which his brother objects to me linking to.