I tried connecting mine up and using DSLstats with a 2-minute sample period. It worked for 5 samples and then started giving login errors. So I'll be interested to see if it does keep running in your case.
A longer period between samples does indeed mean that you'll be missing some short term variations in SNRM and the other time-related graphs, so it's certainly not ideal. As to what they've done, I guess it's a deliberate policy to limit the number of successive telnet logins over some period, for some reason. Maybe it's done for security reasons.