Hang on. Perspective time, maybe?
Remembrance Day originated in Europe as a celebration of the armistice that ended hostilities in WWI. It's not about Americans (those 1918 Johnny-come-latelys), it's not about WWII, it's not about ISIS. So for starters, the question of whether America was ever threatened is irrelevant to the historical significance of Remembrance Day.
Now, to the extent that Americans can appropriate Remembrance Day to say something about American soldiers who died to protect America...well, the most direct expression of that hasn't really occurred since 1900 or so, though one could probably make a better argument for the Pacific theater of WWII counting than the European theater, what with Pearl Harbor. (On the other hand, Germany did declare war on the US before we declared war on them.) On the still more tangential question of protecting American freedoms, we have to go back to the Civil War for a direct example.
But this is a fairly limited definition of protecting America. To take a mundane-seeming contemporary example, much of the practical benefit America enjoys from its modern-day military derives from the Navy's protection of international shipping lanes. It's difficult to overstate the importance of reliable trade routes to the global economy. Protecting American allies and American economic ties is not the same thing as protecting American soil, but it protects America nonetheless.
Or consider the counterfactual: if America had had no military, would its citizens' freedoms have been equally protected? This is not entirely rhetorical, but I do believe one answer is better-supported than the other.
Stepping back from the extremely specific point that was made the focus of discussion, one might say there are other possible justifications for military action besides protecting one's own interests and freedoms. Hitler might not have crossed the Atlantic; do we then let Hitler consume Europe, because our own soil is not threatened? Do we presently believe that, in the service of making sure the US military is only focused on defending American freedom, we should withdraw to our borders and let the rest of the world figure out who's going to fill the power vacuum?
For that matter, do we perhaps have other reasons to remember the troops? Like, say, tens of thousands of homeless vets who need and deserve assistance whether or not you would classify their prior activities as 'protecting American freedoms'?
This is not to offer uncritical support to the military. The US has done many useless things with its military, and many more things that were incredibly fucked up. But it's still in many ways a remarkable institution that deserves our respect and remembrance.
Touching on some other conversations...
-ISIS may have a regional name, but read their propaganda; their ambitions are rather greater.
-ISIS cannot directly remove your legal freedoms, but they could e.g. pose a practical threat to your freedom to assemble at a diner, or a football game, or an opera--never mind what the US might do to its own freedoms, what it has already done to its own freedoms, in the face of terror threats.
-Hitler dreamed of global hegemony, and had designs to attack North America, but neither he nor anyone else deemed invasion and conquest practical. Of course, it's more likely than not he would still have lost WWII if America had never actually entered the European theater, but merely continued its economic assistance to Germany's foes.