You're assuming pursuit. For intercept you don't need a 180mph drone, you just need a somewhat predictable trajectory. You're also assuming constant motion away from shore or other ships, at top speed. Drones with speeds of up to 225kph (140mph) are already in use in Ukraine, although their payload is designed to take down heavy drones and helicopters (only a couple of pounds), and their range is only 12 miles. Nothing a month or two of rather straightforward scale-up couldn't fix. That's before we consider the practical scenario where a larger drone just drops these over the target. And if we assume the adversary is China, there could be hundreds of these larger drones in the air, with dozens of smaller drones each.
I don't doubt that you can physically carry big enough of a payload on an intercept trajectory, I just doubt that a clandestinely manufactured quadcopter will be able to either autonomously track its target (not big enough to carry a radar) or be controllable from 20 miles away (even in Ukraine EW is pervasive).
More realistically they'd try to modify the targeting of their existing AtoA and send fighters. Which is kinda like a bunch of big drones carrying small ones.
Fighters and AtoA are extremely expensive and difficult to manufacture in quantity. You can make drones pretty much anywhere (with a steady supply of cheap flight controllers), for next to nothing, and strap all sorts of payloads to them. If I were the adversary, I'd send a bunch of cheap drones first, to deplete defensive ammo, and then _maybe_ send something heavy duty and expensive. Literally, one single rocket (not to mention a fighter jet) can cost as much as a couple hundred disposable drones. You tell me which is harder to defend against, one rocket or a huge swarm of semi-autonomous drones (computer vision in the terminal phase is quite common by now).
