On the one hand, it is certainly true that many ancient, post-persecution (i.e., Constantine) churches continued to feature altars without reredos (e.g., the Benedictine abbey in Fontgambault; the Dominicain couvent in Avrille built in the 11th century, etc.). Nevertheless, the overwhelming majority (not all) of these churches predated the Protestant heresies regarding the Mass, and the response of the Baroque Church in the face of the Pretestant challenge was to double-down with even more magnificent altars complimented by reredos, baldacchinos, protected by rood screens, etc.
The differentiation between protestant and Catholic worship could be known at a glance from the distinct form of the altar or the table.
Now in the post-conciliar crisis, it is very strange that the FSSPX should begin blurring that distinction and inviting criticism by justifying a return to the "table altar," particularly at a time when the Protestant errors on the Mass have resurfaced within the Church, and at a time when many are worried about the consequences for the Fraternity in preparation for its ralliement to modernist Rome.
Abbe Rutledge seems to be aware of the disturbance this is causing (he begs you to listen to his entire explanation, which is at times archeologistic, just as in the Novus Ordo), and even if the choice in the altar style is mere poor taste and/or imprudence -a verdict which is still to be determined- did he and FSSPX leadership really expect it would pass without a whimper, even amongst branded faithful, particularly when other recent Fraternity church building projects incorporate the same modernist elements (e.g., the table altar in the remodeled chapel in Econe; the monstrosity in Madrid which looks like an LSD-induced dream, etc.)?