Cameron is making decisions every day as PM of far more gravity and with lives at stake. If you don't accept Cameron as a democratically elected leader making decisions that he is elected to make acceptable then you have to admit you don't believe in UK democracy either.Legislation comes from the EU Commission and Commissioners are not elected, they are chosen by the leader (not necessarily government) of each EU member state. I don't call a one-off decision by Cameron democratic given 35k of the UK's 60m people voted for him. I bet the majority of people couldn't name the UK's European Commissioner.
It is deeply misleading and disingenuous to on one hand talk about Europe as almost a dictatorship and undemocratic whilst ignoring how those people get their roles IE through the decisions of the democratically elected models you are promoting . You either respect British democracy and the PMs right to make decisions or you don't. You can't oretend one decision they make is a paragon of democratic virtue and another the same person makes is illegitimate
There are legitimate out reasons , but essentially lying about things and making inconsistent proclamations isn't one