Sorry, wrong again. There is no compulsion to commune at a Catholic funeral. In fact, as an excommunicated* Catholic, you are not even ALLOWED to commune at a Catholic Church!
(*Despite its ecumenism, the Canon Law of the Catholic Church states that Catholics becoming Orthodox like you are schismatics)
Just a side note and I guess to interject a serious thread with some humour, I always ask a friend about where ecumenicism begins and excommunication ends. Anastasios mentioned one example. Then another, I like to tease my Latin theologin,suppose God forbid, I became lapse in my ORthodox faith and became Roman. Well, often standard procedure would be to go back to RCIA or one one one with a priest before recommuning. So, would I go to the Roman Rite, because you're not supposed to change your rite, or would I go to the Byzantine Rite, because Byzantines are not supposed to leave the east, and stay in their rite. AND THEN, what came first the chicken or the egg?!?
Anyways, back to the point, there's no reason to commune at a Catholic, or any non-Orthodox, service. At times, for my work, I am expected to attend a Catholic mass. However, I state clearly that if I must attend, I'm not going to pray and be doing my own silent thing. Reminds me of Shylock's quote, especially looking for Vegan food, during the Dormition Lent . . . for better or worse, lol
I will buy with you, sell with you, talk with you, walk with you, and so following; but I will not eat with you, drink with you, nor pray with you.
That said, I make it clear it's not personal, but rather because of my religious sensiblities, I do not feel comfortable participating in Catholic services. My presence should be support enough. If someone cannot handle that, even at a funeral, then tell them to be a man . . .or a woman, and haven a little of their own political correctness.
Futhermore, where are you basing on things such as the afterlife? Where in the world did you find that in scripture or Church writings? Why do you think during the services, we pray for the Orthodox desceased? Does that mean there are no non-Orthodox believers in Heaven? Of course not, but there is definitly a distinction between the Orthodox Church and everyone else . . .in this world and in the next.