Another option is to switch to the Herbivore Reef Frenzy. It's mostly meat but also contains sizable pieces of macroalgae.
Sometimes it's hit or miss whether blennies will actually consume sheets of algae. Their mouths are 'designed' to scrape algae off surfaces.
If you're lucky your blenny will also eat meaty food. I have a new tailspot in a new nano and was happy to see him eat what the other fish eat, since there's not much algae in there yet.
Also I wouldn't count the blenny out as an aggressor. They can seem peaceful but may sometimes sucker punch another fish if they feel threatened or view it as competition.
One of mine has attacked a Foxface, Coral Beauty, and even a Purple Tang on several occasions. Leaves a nice big mouth-shaped scrape on the other fish's flank.
Like this: