That's always been a thing with any state job, you sacrifice pay, especially starting pay, for benefit and retirement security. This isn't breaking news and those officers should have been well aware of that going into it.
Edit: Just to be clear, I am not suggesting that they don't deserve to make more, I am just pointing out the reality of the situation.
Game wardens have been making the same complaints and publically spoke out at one of the PGC Commission Meetings earlier this year. Challenging situation when you consider union contracts and all.
The low pay is stated in the article as "lower than other law enforcement agencies" which may seem a valid concern, until one compares the requirements, hazards, training, etc. for those other agencies.
I only spent 6 years in the military because private sector pay was a lot higher for doing the same job.