It seems to me that the major problem is that 99.9% of users/miners will have no say whatsoever in this decision, given that the 5-6 biggest pools which mainly have their own hardware control over 75% of the hashrate it is them that will make the decision not us.
The longest bitcoin chain is still the longest bitcoin chain - not altcoin chain - whether it's mined by a million solo miners or 5-6 pools.
What's happening with XT is just par for the course in open source software and I'm surprised it hasn't happened sooner. There doesn't need to be developer consensus and people can release whatever version they like, when they like, so the whole paradigm might as well get tested sooner rather than later as to how the "economy" deals with such diversification.
As to who gets a "say" in what version prevails, it's true that individual end users probably don't have much of a direct influence - relatively speaking. But they do have an aggregated indirect impact I imagine. Miners can migrate between pools or stop mining if they don't like the block acceptance policy, users vote with what clients, exchanges and commercial retailers they use etc.
How the whole ecosystem nets out is anybody's guess but I think it's slightly more complex than just a few pools deciding on behalf of everyone.
At any rate, you can't accuse a developer of wanting to "hijack" the system just for releasing a diversified version when that very diversification is the essence of open source, decentralised software assets such as bitcoin.
Many of the anti-XT lobby seem to have some legitimate technical concerns but the real reason they've sat on their hands in the "scaleability" debate and lost the initiative is strategic, not technical...
"Should bitcoin continue to evolve as an independent, universally accessible, decentralised monetary medium or should its existence and serviceability be made dependent on a proprietary superstructure the way the fiat system is".
Those in the latter camp are in the passive role because bitcoin's design objectives call for the former option and it's incumbent on the developer community to support those objectives IMO.