Ah, alr

still though, the united states alone is far bigger than one nevada in terms of size. I don't think the zeds will be a win button, at least not straight away
The zed's would probably be at a pretty hefty initial disadvantage though, particularly in a country with a large military. It's a virus, so it needs to infect a lot of people to gain traction. Unless nexus core also had time to prepare for such a situation, 2 days of prep is plenty to get the human race ready for a lot of huge stuff, so if this is the case it's definitely going to take a lot longer for zeds to make progress, as long as humans are quick to react, which i think they will be,
even just 5 minutes is more than enough to get a lot of military aircraft in the air if they are on full alert, so 2 days should be enough to get them prepped to do just that
What's the range of the scientists themselves, or their equipment? In the worst case scenario for them, something like an ICBM wouldn't need to detonate all that close to the tower to deal damage or destroy it and not risk getting shot down. Your average, modern-day nuclear weapon can destroy most buildings 12 kilometres (Bout 7.5 miles) away. Unless it's built to take those sorts of energy a direct hit might not be necessary
Of course, humanity's options for taking it out extend far beyond just nukes and ballistic missiles. Artillery, for example, can be spammed in ridiculous numbers, like with the war in ukraine, and can also use
Cluster Munitons, which would be particularly effective against big, stationary targets like the science tower, which the us in particular
has stockpiled in the millions. There's a lot of projectiles they'd need to take out once they are launched, and they'd be getting attacked by air threats at the same time, too, which can also use these weapons from similar distances
The images below gives you a good idea of their range, and for this reason, cluster munitions in particular probably be pretty effective against an onslaught of zeds too if countries aren't willing to drop nukes on their own soil to kill them.