Colic and an infection were two entirely different things. And colic type symptoms aren't colic. Colic is colic, and even then, unless surgery is required (it wasn't), then it's highly unlikely it would have any impact on his ability. A severe infection is something that's treated by antibiotics, and they leave no mark on a horses ability either. The only thing that usually could is if either required surgical intervention. We know that there wasn't. And we know there were no physical issues.
Also, and to be fair to Henderson, he's very open about him. He is not going to come out and make the statements he has if things are otherwise or say something that's untrue. That's just asking for trouble. The racing world would be all over him like a rash. I'm more than happy to take this at face value. Particularly when coupled with my own understanding of it.
I understand why people would be cautious (not least because of being burnt last season), but for me it's a very easy decision. If he's fit and well he wins, and if there's an underlying and lasting condition he may not, but in balance of probability it's highly likely the former. Vet's would advise if it wasn't, and Hendo would either be silent or reluctantly passing on the bad news. There are far too many people involved in the Stable to hide an ongoing issue, or to relay it as something else. It would already be out there in the ether.
Add in that he's the best Champion Hurdler we've seen for a very long time, and at anywhere near his best he's well clear of the Mullins pair. It's not even close. Even if you allowed for some regression he would still win, So at 5/2 he just has to be a bet. If he were evens or shorter I wouldn't be in a rush, but the odds when weighed up against the probability of him retaining his ability are very much in my favour, therefore it's not something I need to think too hard about. Essentially he's easy to back at the price, and he's easy to include in a selection of permutated multiples.
The alternative of waiting is that at 80% fit he will win wherever he starts out, and he'll immediately be 8/11. I hate using them, but the words 'no-brainer' definitely spring to mind in this case.