I can understand why people would want to lock their dogs and why rescues would be against it. While yes, you pay $9 for a color, rescues also have to pay $16-$25. The only perk of being a rescue kennel is getting to rescue dogs. It's been like this since VP was made. Locks, for money or not, don't offer any compensation to rescues who might lose out on a kennel because of it.
I've had dogs rescued in the past. I got angry that I let them sit unattended and angry at the rescues for taking them. I've also rescued dozens of gorgeous dogs, many of which I've kept for the sole reason of keeping them safe. I've also tried to contact people in an attempt to get them to log in before they could be rescued. Sometimes they get on in time, sometimes they don't.
When I know I'm going to be away from the site for a long period of time, I'd either A) give the dogs to someone I trusted, or B) give the log in information to someone I trusted. Back in 2005, I had to move across the country and was without internet for over three months. Jinxx kindly logged into my kennels and took care to make sure my dogs were not rescued. I'm not saying I recommend sharing accounts or giving out your information, but if you've known someone for quite some time and know you can trust them (a friend in real life, family member, etc.) then I say do whatever you can to keep the account semi-active.
In some cases people just can't access internet for over six months. Some of those individuals can't get to a library, friends house, internet capable cell phone, school computer, etc. One of my friends lived in her car/on the streets for over a year. Surviving real life is more important than a game. Stressing over logging in every six months to lose yet another thing just adds more to a persons plate.
However, having dogs rescued previously, I would still never use a lock. I understand that rescues have to do what they can to make their money worthwhile as well. If I made the mistake or if life circumstances lead me to lose anymore, then so be it. Being a sponsor rescue also requires me to understand that, while I've luckily obtained some of these prized dogs, it comes at a cost to the original owner. That said, if someone politely messaged me asking for their dog back, I would do my best to accommodate that request.