I always thought that Reform was in favour of preserving "British culture", so surely efforts to preserve the Cornish language align with that goal?
It always makes me chuckle when you refer to efforts towards preserving minority languages as political when the decline of those languages is partly down to political decisions. The fact that you refer to "dominant national tongues" speaks volumes about your attitude towards minority cultures in this country. Why are Celtic languages spoken so little? I understand that populations migrate and that language changes naturally over time, but the dying back of the Celtic languages wasn't an entirely natural process, was it?
Many of my ancestors would have been Scots Gaelic speakers (Irish and Welsh too, probably), yet I wasn't given the chance to learn that language in school and I grew up in an area where Gaelic would have been fairly widely spoken. Fortunately that situation has now changed and kids these days are able to learn the language of their forebears. It's only right that Cornish people have a chance to learn their own native tongue.
I'm well aware that the dying back of both Welsh and Irish was far from natural; I honestly don't know about Cornish.
More generally, I've a fairly utilitarian view of language which is based in the here and now, and what is of use to people today. So when, a few weeks ago, I heard a teacher in Launceston proudly stating that his school was teaching Cornish as a foreign language, my heart sank at the time that pupils were investing in a language which they are unlikely to use in day to day life, which will not help them elsewhere, and where scarce syllabus time means that they will lose the opportunity to learn foreign languages that may serve them practically.
Nationalists in many places have used language, quite deliberately, as a wedge issue - and Cornish is quite literally the thin end of one such wedge. Where those languages have been dominated by a national tongue, whether that's the Celtic tongues in Britain (English), Breton (French), Czech or Slovak (German, under the Habsburg Empire), Catalan (Spanish), or others, the campaign for language rights has been used as a mobilising force for a nationalist project. It has bound identity with language, and been used to draw points of difference against the ruling power. Sometimes (Irish being a notable example), it has been a conscious top down strategy, at other times it's been more genuinely a bottom up pressure (notably in the Habsburg Empire).
The Cornish project is at the more deliberate end of the spectrum, because the base was so low (see earlier comment about knowledge beyond that). From outside, the campaign seems designed to create a deeper and more separate identity.
For that reason, I don't have a problem with local politicians going "really?" and curtailing funding. What, however, I find grimly amusing is that this is being done by a party that uses identity as a wedge issue, and in a way that could be designed to alienate those who don't feel "English" (and Reform don't understand the difference between "English" and "British").