Deontological ethics need not be drastic ethics ! The term 'deontology' is a made-up modern coinage that derives from the Greek deon (duty - or near enough). Any ethics is deontological if it holds that there are actions or attitudes which are right or wrong not because of their consequences for harm or happiness but because there is something intrinsically morally appropriate or inappropriate about them. A deontologically wrong action doesn't have to be on the moral scale of (say) genocide - a drastic wrong.
For instance, cultural apppropriation has come to be widely resented, and the resentment is moral. It is thought to show disrespect at least where something revered or held sacred in one culture is used for trivial purposes such as toys, ornaments or decorations in another. Deontologically it is considered to be inappropriate because it shows (intrinsic) disrespect and not for any (contingently) injurious consequences it causes - though it may cause such consequences. No deontology that I know of regards cultural appropriation as drastically wrong, as wrong on the scale of genocide.
Johnny Morris' animal voices could be considered a kind of mockery of the animal world or, as you suggest, an inappropriate 'anthropomorphism'. I wouldn't myself take them either way but if they are morally objectionable they could be held to be deontologically wrong because of their intrinsic character. Regardless of their consequences, they embody a morally insensitive attitude towards animals and this is intrinsically wrong.
I am not projecting my own ethical views or attitudes, simply trying to show (1) that Johnny Morris' voices, which few would regard as major evils ('drastic'), might none the less fall under a deontological ban; and (2) more generally that deontolological moral judgements apply to actions or atttitudes considered to be intrinsically morally appropriate or inappropriate regardless of the scale of their rightness or wrongness. There is no special conceptual connexion between the deontological and the drastic.