One consideration is processing capacity. The E-350 is dual-core, single-threaded 1.6 GHz and, depending on chipset, might be limited to 4 or 8 GB RAM. Would that be sufficient for your bandwidth and intended processes such as IPS & Clamav ? If not then you would need to investigate a different APU anyway.
I doubt that there is a simple answer to your question regarding vulnerability. In the absence of any first-hand reports, on this forum, for contemporary Intel processors you could not purchase one and be confident that it is less vulnerable than the E-350. The older Intel Core 2 Duo generation certainly weren’t.
I too have an E-350 and Specter Meltdown Checker reports similarly for it. All other AMD APU that I have run the checker on get a satisfactory report for this particular vulnerability:
A-series report “mitigated” - those would be a better solution, for outlay of about USD 150
older Turion series report “not affected”, if you have any of those.