This is a common argument that I usually see people making, there are a few big problems though with the idea of just getting new moderators. The first problem is that moderation is difficult. It's really easy to look at online posts talking shit about moderators and think that you could do a better job than them but you couldn't and neither could most people, it is a very tedious and difficult process, while there may be many people who are willing to do it there are not as many people who are cut out to do it.
The second problem is that the API changes that Reddit has imposed will make content moderation ever more difficult due to the loss of automated tools that help. People are going to bring up reddit's promise to bring moderating tools to the mobile app or to improve moderation tools in general, this is most certainly an empty promise and even if fulfilled they will do the absolute bare minimum. This is a problem because it means that even for seasoned moderators content moderation is going to become increasingly difficult. Now imagine for somebody who isn't a seasoned veteran moderator, who was freshly appointed by Reddit's administration to fill the roles of mods who quit. I imagine they're probably not going to be able to do this job effectively.
Even If you hired a paid moderator team they would still be nowhere near as effective as the volunteers who poured their heart and soul into it, especially considering that those moderators will be working regular jobs. They're not going to be able to moderate to the lengths that an unpaid volunteer could. This is also ignoring the fact that Reddit very much cannot afford to appoint paid administrators to moderate all of the largest subs on Reddit, considering that making a lot of money is their goal that just isn't sustainable.
So yeah while they could get new moderators it would not be a very easy task for them, and would definitely come with severe drawbacks.
Obviously Steve Huffman doesn't really care, he'll probably try it anyway and who knows maybe it'll seem to work out short term, the new moderators won't really be put to the test until they have to deal with a large scale bot attack, either coordinated or uncoordinated.
A good thing to keep in mind is that the scammers are watching this scenario, they've already started using it to their advantage by messaging moderators pretending to be administrators as a phishing attack.
An experienced mod might be able to Ward this off or not be affected, but in unexperienced mod may fall for this kind of attack without knowing better.