Ann: Firebrick Update on Phase 2 Trial Results, page-4

Heparin is not absorbed into bloodstream and topically applied doesn't cause bleeding.
It binds with virus is the theory

They may have trouble getting trial recruited due to few people actually reporting covid infection unless requesting antivirals or being in employment where testing is still required like aged care and where imnosuppresed people are involved like cancer patients etc.

I hope they have sucess as more arms to fight virus the better but each will have a specific role going forward. This trial is very much about post infection slowing spread to close contacts

Clinical trial website

https://classic.clinicaltrials.gov/ct2/show/NCT05204550

Website
https://www.nh.org.au/inherit-the-intranasal-heparin-trial/