It is consistent for the government to support fptp

Tactical voting is bad because it means that voters are not getting what they want... and this always means freedom is being reduced. If people vote tactically for the centre-left party we can reliably say that they are more economically liberal than the party they are voting for. (Otherwise they would not be voting tactically but in earnest.) If people vote tactically for the centre-right party they are more socially liberal than the party. Economic and social authoritarians in each party prosper because of tactical voting.