It’s not clear if Dutton is actually praising Cobbett.
I suspect there was always the possibility of a satirical sense to terrific in the Romantic period. Thoroughgoing Romantics so prized the ‘terrific’ that anyone not romantic it was an obvious quality to parody.
I’m particularly fond of this verse in Peter Pindar’s The Disappointed Duke (a satire on the events of 1818 in England. The Princess Charlotte, the Prince Regent’s only child, having died in childbirth, the Prince Regent’s younger brothers instantly cast off their mistresses (some of more than a decades’ standing) and cast about for someone to marry, to produce a legitimate heir to the throne):
Agog are all, both old and young,
Warm’d with desire to be prolific;
And prompt with resolution strong,
To fight in Hymen’s war terrific.