Hi @bptxmn, welcome! Apologies for the delay. Using the iNaturalist logo to add a link to your iNaturalist project from the Master Naturalists page is definitely ok. You don’t need our approval to use the logo in editorial contexts (i.e. writing about iNaturalist) or referral contexts (what you’re doing here with linking to an iNaturalist project page).
I recommend that you use one of the logos available on our press page. For convenience I’m also uploading just the iNaturalist wordmark here that you can use without the bird attached or .org.
Thanks for checking the Terms of Service, @mftasp. It’s intended more to clarify that you can’t use our logo to go make & sell “iNaturalist binoculars” or something. I will note that we should try to clarify permission for the use case @bptxmn describes.