It's not the loosening that causes irreparable damage so much as not noticing it, or noticing but trying to ride home anyway. Initial loosening may cause a little deformation in the crank taper but usually not so much that it prevents refitting and continued use. If in doubt carry the tools you need to tighten the crank bolt. Were old TA crank bolts the same M8×1.0 as modern cranks? I don't recall, but if so just carry a spare modern crank bolt and an 8 mm Allen key.