NO absolutely not, all that will do is give it 4 pivot points to fall over with.
I tried that with my 210 but verticles are needed every 16" maximum.
I built mine with a floor and a tank platform then cut my verticles to length and screwed them in, all 210g full is supported by the wood, when fastening make sure the weight is on the wood not the fasteners.
Mine is not in wall but atleast it will give you an idea.
and where I had to reinforce due to swaying movement.
again its not inwall but it might help you, My stand is 24" tall so I can reach in and see over the top a bit. It sits just about 5' tall.
My uncle bought our old 90g off us and turned it into a marine in wall unit. he used 4x4's for the support. and his stand was part of the stud wall.
try this site, I just found it on google using different terms for in wall tank stand diy plans
FishandTips.com: do it yourself aquarium stands