What happened in the past was the 2017 Las Vegas mass shooting [1] - the deadliest mass shooting by a lone gunman in American history. It was conducted by shooting out of a hotel room window. The shooter had 24 guns and over a thousand rounds of ammunition in the hotel room - which went unnoticed partly because the guest put up the 'do not disturb' sign.
The hotel owners have presumably decided that the high-probability-minor-damage risk to their business from a few paranoid types avoiding their hotel is not as great as the very-low-probability-enormous-damage risk from a copycat mass shooting.
And so, ignoring the do-not-disturb sign and snooping on guests' rooms is the norm in Vegas these days.
And if they happen to have a large block booking of particularly privacy-conscious people and so a noticeable fraction of the rooms are declining maid service, I can understand why they'd want to be ready to carry out some supplemental checks.
The guns are on a separate list for an existing protocol. This is just an extention, probably temporary and only applied to DEFCON guests. The point is that the prior attack has chance how the industry views room privacy vs guest safety (liability) for any type illegal activity (even if there's no indication the tools are being used illegally).
I aee a lot of disagreement here. It's not that it's specific to DEFCON of "hacking equiptment". It's that the prior attack has given hotels the will and potential legal cover to do room checks/searches. They can now apply this to anything, such as "hacking" equiptment, guns, hotplates, etc. There are even examples of hotels handing over property from rooms or valets to law enforcement without a warrant.
A small number of Walter Mitty types believe hotel maids are planning to hide undetectable snooping devices inside their electronic devices - a so-called "evil maid attack" - and so choose not to have their room cleaned.
In the normal operation of a hotel, such guests are uncommon - but I expect defcon attracts several orders of magnitude more such people.
The hotel owners have presumably decided that the high-probability-minor-damage risk to their business from a few paranoid types avoiding their hotel is not as great as the very-low-probability-enormous-damage risk from a copycat mass shooting.
And so, ignoring the do-not-disturb sign and snooping on guests' rooms is the norm in Vegas these days.
And if they happen to have a large block booking of particularly privacy-conscious people and so a noticeable fraction of the rooms are declining maid service, I can understand why they'd want to be ready to carry out some supplemental checks.
[1] https://en.wikipedia.org/wiki/2017_Las_Vegas_shooting