Well (as I posted earlier in the thread), I was accepted to the LinkedIn SCP group within about 3 days. Not sure why that process was so smooth for me and not for others.
I'm sure it's obvious, but I note the original post doesn't actually include the instruction to "Join" the SolarWinds Certified Professionals group on LinkedIn, which I had done prior to emailing the Certification address.
Anyway, after 3 months, and like many others it seems, I'm still waiting for the SCP Thwack badge and the mythical welcome pack so perhaps one out three aint bad.