While it is true, that today the subsidy from Denmark is minor relative to Faroese GDP, to a point where one might wonder why they need the money at all? (Besides, I don't think I made any actual specific references to that subsidy.)
The infrastructure, I am referring to, was built several decades ago (with the exception of some newer additions that was built by the Faroese themselves, like the Norðoyatunnilin), at a time where the Faroese GDP was much lower.
In particular, Denmark had to bail out the Faroese Islands during their financial crisis from 1989 to 1995, through loans.
When I say 'reliant' on Denmark, I don't mean in direct financial terms. I mean in terms of foreign, military and judicial dependence. In 2005, Denmark gave the Faroese government permission to establish Faroese missions within Danish embassies. That's a huge advantage to them, being able to use existing Danish infrastructure for their foreign endeavours.
Indeed, the agreement of 2005, the so-called "Fámjin Declaration", has practically eased tensions between Denmark and the Faroese Islands, and calls for independence gets very little press time any more.
And lastly, the subsidy you refer to is just the subsidy in direct cash from the Danish government, there are several other ways Denmark supports the Faroese, both nationally and internationally, which value would probably be far larger than the subsidy itself. To summarise; it is an advantage for the Faroese Islands to remain part of the Kingdom of Denmark.