No I highly doubt it. This is most likely as they say a GDPR issue. Per the GDPR they'll have to keep track of which users have agreed to which version of the ToS and Privacy Policy and make sure that they only process their data in accordance. This is a PITA, much easier to deem accounts inactive and delete their data. They've probably been contacted by the data commissioner of some EU country and asked nicely to comply with the GDPR.
A second, somewhat related issue, is that these inactive accounts might also be used by all the russian state trolls. It's much harder to detect when old accounts start doing suspicious things than brand new ones, especially if you don't have a robust process in place for flagging inactive users.
We're talking about users that last logged in more than 6 month ago here. It has obviously nothing to do with government sponsored shills or the GDPR. It's just that Twitter wants to eliminate users that are not "monetizable", they are also looking into users I quote "log in but don't do anything" on Twitter.
Actually, under the GDPR, as a general rule, you can't just keep personal data on your servers forever so GDPR might be involved but for personal data cleanup reasons/requirements.
A second, somewhat related issue, is that these inactive accounts might also be used by all the russian state trolls. It's much harder to detect when old accounts start doing suspicious things than brand new ones, especially if you don't have a robust process in place for flagging inactive users.