With the VirusScan Command Line Scanner it's more a matter of Library & kernel support than 32 vs 64-bit.
From the readme System Requirements:
- Linux for Intel 32-bit distributions with
libstdc++.so.5.0.5 or later installed
- Linux for Intel 64-bit distributions shipping
with version 2.6 production kernel, with
It's conceivable in the right circumstances and with appropriate legacy library support you could use either.
if it's running you won't be losing out, 32 & 64-bit versions are functionally equivalent