A gastroenterologist will do the procedure in an endoscopy suite, not radiology. In fact, the doc you were referred to has a financial interest in a multi-site endoscopy practice (Dallas Endoscopy Centers). Is it the ALS clinic that referred you? Certainly, you can meet with him and see what you think (ask about RIGs in ALS and you may get an idea about how much he knows re ALS). But you have no obligation to buy, as they say.
Yes, sugar can put a greater demand on the heart...but shouldn't affect diastolic pressure. I buy Breyers ice cream, which has mostly natural ingredients with less sugar.
So the diastolic BP has been higher than 90 in the measurements you report -- that's of some concern and so they may well suggest he start a BP med. I would ask for a calcium channel blocker like diltiazem ER (24-hour formulations are less likely to cause side effects) if he has no contraindications to one. "Normal" people are often started with a diuretic but that's not recommended in ALS. Ironically, feeling anxious about his heart is of course likely to increase his BP and pulse. Can't remember how long he's been on the SSRI?
Re sertaline, different SSRIs work for different people, so after several weeks if it doesn't seem the right thing, ask for another. Some SSRIs are more sedating and some are more energizing. Zoloft is somewhere in between.