I doubt many young people even want "long term" prospects anymore.
Job security was the number one concern overall (63% of said so). Income was only in fifth place. There was a big difference between the sexes, the share of women who wanted to work for the government was much higher (42% vs. 23% of men).
But that's not all - most students prefer to work for very large companies, giants like Siemens, BMW etc. regularly top the ranking of places where students want to go to. Few want to go to small and medium companies, even though we have a lot of them. Even fewer want to work for a startup or even found one.
I am certainly not critical of that attitude, I doubt that throughout history there ever was a big part of humanity that preferred insecurity and excitement and (often dubious) "chances" that actually depend on quite a bit of luck quite heavily over friends, family and a solid secure basis. That is if that was available of course, often people were forced into being more adventurous by circumstances.
[0] (in German) http://www.spiegel.de/karriere/berufsstart/jeder-dritte-stud...
[1] (PDF) http://www.ey.com/Publication/vwLUAssets/EY-Studentenstudie-...
The article is from German media. I can't speak for the US, but in Germany it leaves a bad impression if you switch jobs too often. Also in the last 15 years (in particular under the Schröder administration (from 1998-2005)) in Germany there were lots of reforms of the job market that lead to the feeling of many people that the jobs are much less secure and if you lose the job you will move downward socially much faster. This in my opinion explains pretty well why now lots of people want jobs that are more safe. And I see no evidence that this doesn't hold for hackers, too, since it is well-known that it is much more difficult to find a new job in the technology sector in Germany if you are, older than say, 45 years.
Besides, if talented hackers were so majorly set on permanence in their jobs, there'd be no game studios.
That link also doesn't say anything about long-term prospects. It does say it can't pay the lucrative amounts the private sector can, but that doesn't mean that the pay is 'unreasonable'. In fact, most of that article is about a mismatch of cultural fit, and has very little to do with remuneration.
And seriously, given how much of the hot talent in SV jumps around on a yearly basis depending on who provides the biggest bucks, does anyone really believe that "long-term career prospects" are going to appeal to those hackers? Do talented programmers really sign on to Apple because "I know I'll be a senior manager there in 20 years?
'Job security' is not the same as 'long term prospects'.
This is just a stupid excuse for why he is not doing his job effectively.