Objecting to word usages of others does not alone make one a prescriptivist, but the nonprescriptivist who does that is nonetheless likely to be taken by some for a prescriptivist.
This is where the word
proscriptivist comes in handy. The classic proscriptivists may have a stable of prescriptions to fall back on but their motivation is in supressing usages other than those they use themselves.
Dictionary.com: No results found for objectionist.
There's probably a lot of words of the form ROOT+ist that don't have primary entries.
