This is fine until something uses more memory than is available, such as sox insisting on routing a huge audio file though a too-small /tmp, or the MATLAB installer likewise only using /tmp. With sox you could in theory recompile to get it to use some other path (iirc none of the TMP or TMPDIR environment variables did anything), but I instead gave up on the /tmp in memory (it complicated the OpenBSD desktop setup). I forget exactly how I worked around the MATLAB installer issue, probably something horrible involving LD_PRELOAD or time wasted reconfiguring and rebooting and reconfiguring and rebooting one node to do the install on, plus more time wasted running the massive and bloated installer process(es) under strace to see exactly what file paths were in play.
So, not really a fan of /tmp in memory. (And I don't much run massive and bloated browsers that may murder your SSD lifetime with excessive file writes better diverted to an in-memory /tmp.)