I’d actually been enjoying the programme that replaced Material World, but last week we had a justification of the host, no less, saying last week “a bacteria” (the singular is actually bacteriUM).
The usual excuse for such language errors is that language is an evolutionary thing: it happens. It’s natural.
Yup, same with murder, abuse, theft, war, disease etc. etc. So the best thing to do with them is just say “They’re all just natural things! It’s OK to let them happen!”
Just because lots of people get something wrong, it doesn’t mean it’s now right.
And if it’s ok for a language feature to change, it’s also ok for it not to change.
In any case, we can see it’s unlikely to be a transference to the regular form, where the plural just adds an S. Instead, it appears the new form is more of the “one sheep, two sheep” type.
The reason people support this kind of mistake is because of justifiable support for local dialects. That is not the same thing as getting something wrong.