Employees aren't feudal servants who are subject to their masters, they are suppliers from whom you are purchasing labor. Obviously that labor is for sale, otherwise you wouldn't be able to buy it in the first place. Sure, you'd like to be treated as a monoposony purchaser, rather than an option in a marketplace, but equally obviously any supplier of labor would be foolish to treat you that way.

Who doesn't have a dollar amount that they're willing to walk away from a job for? I've been personal friends with many of my old managers; not one of them didn't understand when I left for a role for a significant pay increase. One of them was even joking with me one day about the talk he had with his manager on what they would have to do to retain me, and his answer was, "they offered him $50k more than we pay him, we won't be retaining him." And most of them were talking to me about their next role's pay bump at one point or another too. And let's say I was working for you, and out of the blue a friend from a previous job is hiring for their team and offers me a similar position for $50k more per year than you're paying me, I'm not going to not take it out of some sense of loyalty. In the words of the wise, "there's always a price and everything is for sale." The products your company offers is generally for sale for as much as is economically feasible, the same way your engineers are selling you their time.

Anyway, your overall point is that as a hiring manager you don't want to stake your time and reputation on people that seem disloyal. My point is both that people are inherently disloyal with their employers (in that their loyalty costs money), and that the signals you use to judge loyalty are, in my opinion, flawed. I can go into why I'm of that opinion, but it's my lesser of the two opinions.

Is loyalty actually a tale to tell to your employee to keep them in while suppressing pay rise?