I can't see how it's Authoritanarianism personally. I mean if coersion was going to exist it would exist with people going around bullying people to vote a given way irrespective of if people were obliged to vote, so I don't understand the bully boy/stooges relevance. If it's the right to not vote for any of the canditates that's an issue, well mandatory voting doesn't require that you have to choose a candidate any more than staying away from the polls does now. You'd just have a optioned named "none of the above". If anything I'd say it's far better to actually count that "anti" vote than not. Currently you just don't know why people didn't vote.
If anything I have an opposite view. People died to protect our right to maintain a democracy against an authoritarian regime, in my view voting is a privilege that we shouldn't take for granted and thus I feel it's our civic duty to at the very least "express our opinion" in the democratic system, be that chose a candidate or say "f*ck off". Either way I think it's important the view is counted. In a way I also see it as a form of "rememberance" of those that died to protect our democracy.
Of course a lot of work would need to be done in order to make sure voting is easy, pain free and convenient so that those who are less mobile etc can have their say. It also needs to be impossible to corrupt.