I wouldn't say there's a non-trivial chance that they'll be fired in 1-2 months. Being able to effectively screen people is another technical managerial skill. There is a very, very small percentage of candidates that make it through the interview and later turn out to be duds.

I think there are two issues at play:

1. Ineffective managers are terrified of firing people.

2. Ineffective managers rightly or wrongly think they can't screen people without code tests, white boarding...

Like I said in my original comment I look at their Github or any other work portfolio they provide and have a deep discussion about it with them.