1)

The RE'AH follows the simple reading of the Gemara. It is only for the esophagus and the lung that the Gemara states explicitly that the hole cannot be sealed.

(a) Rabah says (end of 43a) that if a scab formed on a hole in the esophagus, it is not considered a seal to permit the animal.

(b) Rav Yosef says (47b) that if a scab formed on a hole in the lung, it is not considered a seal to permit the animal.

Since the Gemara said only that a wound in the esophagus and the lung cannot be effectively sealed by a scab, it follows that all the other organs of the body can be sealed if wounded.

2)

The Ran (end of 8b to beginning of 9a in the pages of the Rif) cites support for Rashi's opinion that a seal does not permit a Tereifah caused by a hole in any limb, not just in the esophagus and lung. The support is from the Gemara on 48a which cites a Beraisa that if a man's reproductive organ was perforated, he is a Patzu'a Daka and may not marry, but if it was then sealed he may marry. This is a Pesul that can become permitted. The Beraisa states that this excludes a scab that formed on a hole in the lung, which is not effective in permitting the animal.

The Ran writes that the intention of the Gemara is clearly not to exclude only the lung, since the Beraisa did not mention the lung. Rather, the inference is from the phrase "this excludes" which teaches that this is a Din for Patzu'a Daka but not for any Tereifah. Concerning all limbs of the animal that were perforated, the scab cannot make the animal permitted again.

3) Here are other opinions in the Rishonim who agree with the Re'ah and their reasoning:

First, let me cite where the Re'ah writes his opinion. It is in Bedek ha'Bayis, which is his work written on the Toras ha'Bayis of the Rashba (the Rashba and Re'ah were contemporaries; both were students of the Ramban, and the discussion between them is sometimes fierce). It is in the "Bayis Sheni," "Sha'ar Shlishi" of Toras ha'Bayis, on page 68 of the older, standard edition. The Re'ah simply writes that since the Gemara mentions only two organs, the lung and esophagus, where the scab that develops through the wound is not an effective seal, this implies that for all other organs the scab is an effective seal.

a) The Ra'avan (who was a colleague of Rabeinu Tam and lived over 150 years before the Re'ah) on Maseches Chulin #226 writes that the reason why the scab that formed on the wound of the esophagus is not an effective seal is because of what Rav Ashi (43a) states, that the esophagus expands during digestion and respiration. The Ra'avan writes that because of this expansion, the hole will re-appear even though originally it sealed up. It seems that it is the natural movement of the esophagus that prevents the seal from being permanent.

b) The Ra'avan explains why the esophagus cannot be sealed but he does not explain why the lung cannot be. However, the Teshuvos Avnei Nezer (YD 61:2) explains the reasoning of the Ra'avan. What we just cited in the name of Rav Ashi was to explain why, if both membranes of the esophagus are punctured but in different places, the animal is Tereifah because of the expansion of the esophagus. The Hagahos Ashiri (on the Rosh 3:13, DH v'Im) writes that the same applies to the membranes of the lung. If they are both punctured, but in a different place, this is also Tereifah, because the lung absorbs all kinds of liquids, makes a noise and contracts and expands. This activity of the lung is similar to the activity of the esophagus. Just as it makes the esophagus and lung Tereifah even though the holes are not opposite each other, it also causes the dismantling of a scab that formed, but for other organs that do not experience this movement the scab that formed remains and continues to seal effectively.

Kol Tuv,

Dovid Bloom