Aside from the poor start he had, one could also argue that the trip at Aintree may have also been an issue – the Irish and Welsh Nationals are 3m5f and 3m6½F so we are talking about another 4½F to 5F further, so he still has that stamina angle to prove but I personally don’t think the weight was an issue, as he carried 3lbs more when winning the Welsh National off 11-13.
That being said, he was coming off a Gold Cup campaign and I truly believe this was an after thought to go to Aintree especially off a hard race in the Gold Cup (a lot of those that ran well at Cheltenham went on to run flat at Aintree). So that could be a major factor in his poor run and as such you could give him the benefit of the doubt.
So if they gear a campaign specifically around Aintree with a maximum of three runs beforehand (rather than Aintree being his 6th run of the season like it was this time), then I think he would be a major contender to add to his National hauls.