why would they use Houston?
Because they couldn't get through the crowd at the front door, and they were at the south east corner of the TSBD ( Houston & Elm) So the quickest route to the 5th floor was by way of the sidewalk along the east side of the TSBD ( along Houston street)
Yes, that works.
And, Oswald did the same thing at 12:32, he walked from the SE cnr of the TSBD towards the NE cnr, to enter the TSBD to get his jacket laying in that same window. But he stopped & did a u-turn koz he saw Officer Barnett standing at the NE cnr. Frazier saw Oswald walking south along Houston (& then probly saw Oswald crossing Houston).
Frazier didn’t say, but if Frazier woz close enuff Frazier would have heard Oswald's tummy growling, koz Oswald hadnt had any lunch.
So, why would Oswald be sitting in the Domino Room if Oswald didn’t bring any lunch?
[edit 4june2022][A caterer sold lunches outside at 10 am each workday, hence Oswald could have bort lunch that day.]
[But if he had bort lunch then he would have said so][But if he had bort lunch then would he really have bort the same cheese sandwich & apple that he usually brort from Marina's place?][Marina said that Oswald sometimes bort a hamburger, i think that this would have been from this caterer}
https://www.jfkassassinationforum.com/index.php/topic,2940.msg111780.html#msg111780Baker & Truly managed to get onto the roof at about 12:33, by using a fixed ladder to the trapdoor, the stairway from Floor-7 being locked.