No, I don't see it as such. I figure that respect is earned and lost. But it sounds like you're suggesting I'm being insincere. You might consider that "Respectfully" simply conveys "I mean no disrespect".
Euthanasia and compassion are not the same thing because euthanasia is a chosen course of action. While I agree that out of compassion a person would want to end, and not prolong, the suffering of someone who is terminally ill by putting them to death painlessly, that does not qualify as an immoral intention or goal any more than giving them morphine or any other painkiller to ease their passing. Hence the claim that you're "conflating compassion with a definition of compassion" can only mean that you are aware that compassion would never desire to prolong the suffering of others.
The objective fact of the matter is that Compassion is not the product of any mental deliberation, it's a heartfelt reaction to seeing the suffering of others and wanting to ease that suffering. The scenario you present is a mental deliberation after the fact, because it's a difficult decision whether it's right or wrong to take someone's life in such a circumstance. Therefore, it's a semantical construct to frame the question as whether they should be compassionate or not, because this conflates the heartfelt compassion with the mental deliberation of whether it's right or wrong to euthanize.