Using a product and hosting commercials for them are two different things though. If Eero stops being a sponsor Im positive there will be another company to fill that slot, its a popular podcast with a large audience reach.
Marco Arment is not exactly a starving indie developer and podcaster between the equity he had in Tumblr. Whatever he got from selling Instapaper, running his own successful ad network for Overcast.
On top of that, he was an early investor in Gimlet Media that just got acquired.