The right to vote is completely mutually exclusive to whether or not someone violates a law

I would argue that this is the exact kind of rhetoric a government would use (and has used) to deny voting rights to anyone who they perceive as "anti-American". In fact, this is the foundation of many of our historically racist laws, in which the government would create and crack down on laws that disproportionately affected certain minorities, in an attempt to disenfranchise specific groups of people that the state deemed a threat to the status quo. There is simply no non-malevolent reason for denying people voting rights.

I'm curious on your thoughts on this, and how you would propose we could mitigate such a risk while maintaining the principle of universal suffrage.

First of all, there is no real risk. There is no evidence to even suggest the idea that there is such a significant number of terrorists in this country as to be able to sway an election; it is a completely nonsensical hypothetical, nor should it be used as grounds to deny voting rights.

This issue is simple: a democracy means that all people have an equal say, so if certain people are denied their say, then the system is no longer a democracy.