Currently the TagHelpers don't have an option to render deferred scripts, like the HTML helpers. It's a valid request and I would encourage you to log it into our public uservoice, so that other people can vote for it, and we will consider it for our future releases:
Telerik by Progress
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Feedback Portal
and vote to affect the priority of the items