No, you do not have to seal porcelain - it is not porous.
You need to remove the haze according to the Spectralock instructions. It is easier to do with a mix of vinegar and water (1/2c to 1 gal). Do not wait too long - it would be very hard to do if you miss the right window for this. Hard, but not impossible - there are some chemicals that help to remove epoxy haze :)

Thanks Alina_1 for responding. Your comments are reassuring.

I have used Spectralock on my other projects but one was stone where I did apply a sealer first. The other materials were glazed ceramics with a very high gloss finish. The tile I have now is very fine and smooth in texture, just unglazed.

This morning I have read on the JB forum that if your porcelain has been polished, a sealer is needed. I believe the term "Polished" means mechanically polished. The statement was that polishing opens the pores of the porcelain. I don't know, but oh well, not my situation. I was looking for info on grout releasing capacities with rougher surfaces, non-glazed, and epoxy. Did find a thread with 50/50 views on the need (or not) for grout release/sealer. I don't know what the OP went with, he didn't state. His floor looked good and it was WAY courser than my tile. Mine is just matte finished per manufacture.

Guess what, I called the tech department earlier (insinuating that I was a designer/architect so I could get a live person on the line) and the guy said to use Miracle grout release product. So I went on line to the Miracle site and there is not a "grout release" product that I could find. Though I believe their sealers can help with grout release. I agree with you about the porosity of porcelain, minuscule. Also on another JB thread I noted that some were cleaning 3 times following the application. First 2 as instructed, and it sounds like the 3rd about an hour following the second one, all with either the vinegar solution or the enclosed rinse product.

I am proceeding without an application of anything. I will wash 3 times. The tiles are large, so I will try to just get grout on the grout lines as best I can.

Now I am measuring out my parts A & B on my kitchen scale. I bought a full pail of Spectralock Pro Premium online last winter and will probably only need about a 1/3. I've had very good luck with measuring and customizing my colorants.

Good luck with it!
We've used Spectralock with both glazed and through-body porcelain and with travertine. We sealed the travertine before grouting, but we did not pre-treat porcelain. I learned that the key to successful epoxy grouting is organization - prepare everything you might need, get some extra sponges, plan your schedule so you clean the haze in time, etc. Removing the haze 12-24 hours after the application worked fine for us with any tile material.

I used Spectralock epoxy grout on many square feet of porcelain tile and never sealed any of it, all without ill effect. Do make sure you clean it well. 3 times isn't a bad idea. Also, keep in mind that there's a limited work time on the grout. So either make up small batches or put part of it aside in the freezer to slow down the chemical process. I usually worked with 1/3 of the batch at a time. No problems using the freezer stuff even 24 hours after mixing.

Thanks Weedyacres, I too have used the freezer system in my other bathroom tile work. I first heard of that trick on the JB forum last year. It works well a day (or 2 later). But after 2 weeks, it's no good. I love that this works, for those pin holes you see the next day.

I cleaned each tile 4 to 5 times. There was quite a bit of shine left over with the epoxy after the 3rd wash. I just kept at it with the the vinegar wash. I used a microfiber cloth on the 4th and 5th cleaning. I also wrapped a scrapper in the cloth so I could really bear down on the surface with the microfiber. Each tile is now matte again.

If I had to do it again, with this fine grained tile, I would try a grout release product like the Laticrete tech recommended. But the only release I found online was by Aqua? or something like that. If the grout release coats the surface and prevents the epoxy from contacting the porcelain face, I think it would help.

Thanks everyone for your support and help with this issue.