SOLUTION:
reset environment variables to allow steam to run normally. Partial fix is using sudo to reset the environment, through another user.

Attached verbose steam logs
log_xinit.txt
log_2bwm.txt

Your system information

• Steam client version (build number or date):
  Mar 22 2018
• Distribution (e.g. Ubuntu):
  Gentoo
• Opted into Steam client beta?: [Yes/No]
  No
• Have you checked for system updates?: [Yes/No]
  Yes

Please describe your issue in as much detail as possible:

a particular window manager (2bwm) breaks access to library when running steam
($HOME/.local/share/Steam)

Possibly associated with a _NET standard, given the WM covers little

Multiple casualties with using the same WM. (It would be a bummer to deem it unsolvable)

Running Steam with xinit doesn't have the issue.

Steps for reproducing this issue:

Particular steps have worked to run steam normally

1. Run 2bwm
2. Install steam
3. Remove problematic bundled library incompatibilities
   $ find ~/.steam/root/ ( -name "libgcc_s.so*" -o -name "libstdc++.so*" -o -name "libxcb.so*" -o -name "libgpg-error.so*" ) -print -delete
   To make steam even launch
4. Open steam
5. Settings>Downloads>Steam Library Folders button, dialogue gets stuck on "Searching", and adding any other location fails with "New Steam library folder must be on a filesystem mounted with execute permissions"