Daf Yomi - Sukkah 25 - Eating Neveila while Performing a Mitzva

Tosfos maintains that one who is busy with the mitzva of returning someone's lost object is exempt from giving tzedaka to a poor person. Busy is defined as being involved and preoccupied with the lost object, such as feeding an animal.

Maharatz Chayus is bothered with a strong question on tosfos. He states that besides for there being a positive commandment of sustaining the poor, there is a lo saaseh of closing one's hand by not giving the poor person. This is why beis din can compel someone to give tzedaka for there is a lav as well. if so, he asks, there cannot be an exemption of giving tzedaka to an oni when he is involved with a lost object for the principle of osek b'mitzva only applies by a positive commandment and not by a neative one?

Would someone who is busy performing a mitzva be permitted to eat neveila?

He leaves this question unresolved.