I don’t think anyone bemoans making paths more accessible for the less able but in this instance you have to ask whether this was the best bridleway to do it on?
Mtb’s will now probably use the adjacent footpath instead unless the NT think they have to restrict access to bikes and put some form of other access control in place.
The money spent here could have paid for improved access on paths more likely to get more use by less able bodied.
The biggest barrier to use of the countryside for most of the population is actually getting to the countryside in the first place, the second biggest barrier is information – when I get there where should I go where will I be able to go? what should I expect when I get there?
Putting barrow loads of gravel on a steep path at the end of a steep tarmac road I doubt will benefit a great many people that could not have previously walked the path anyway.