It does provide full RAM access actually as long as you launch it from a game but what you should do is just put back the hbl.nsp and hbmenu.nro from Atmosphere. hbl.nsp is in the atmosphere folder whereas hbmenu.nro is on the root.
hbmenu.nro is where Mercury is contained and it basically hijacks your HBL. I was puzzled when I saw that it was no longer booting into HBL and promptly changed the files back as Mercury seemed super sketchy and sneaking that in there without telling people is not OK.
hbl.nsp is just a modified or outdated version that allocates the maximum RAM available, if you've seen the Tinfoil changelog you might have noticed him complaining about Atmosphere reducing the available amount of RAM in applet mode to allow the soft keyboard to work in homebrew. There is a setting in one of the Atmosphere inis now to adjust the RAM allocation in applet mode though I'm not sure what it should be set to to achieve the same effect.
Tinfoil "needs" that extra RAM in applet mode or some features might not work correctly, but if you just launch HBL in game mode it doesn't matter and you are just as well off using the stock Atmosphere hbmenu.nro and hbl.nsp like I do.
In fact I don't even use most of the files from the hbgshop release. I grab stock Tinfoil and add the required files from hbgshop (minus anything executable) just in case, you never know when someone might decide to put malware in it. I don't particularly trust anything executable that comes from a warez group.